QSqlQuery#
The QSqlQuery
class provides a means of executing and manipulating SQL statements. More…
Synopsis#
Functions#
def
addBindValue
(val[, type=QSql.In])def
at
()def
bindValue
(pos, val[, type=QSql.In])def
bindValue
(placeholder, val[, type=QSql.In])def
boundValue
(placeholder)def
boundValue
(pos)def
boundValueName
(pos)def
boundValueNames
()def
boundValues
()def
clear
()def
driver
()def
exec
(query)def
exec
()def
execBatch
([mode=QSqlQuery.BatchExecutionMode.ValuesAsRows])def
exec_
()def
exec_
(arg__1)def
executedQuery
()def
finish
()def
first
()def
isActive
()def
isForwardOnly
()def
isNull
(field)def
isNull
(name)def
isSelect
()def
isValid
()def
last
()def
lastError
()def
lastInsertId
()def
lastQuery
()def
next
()def
nextResult
()def
numRowsAffected
()def
numericalPrecisionPolicy
()def
prepare
(query)def
previous
()def
record
()def
result
()def
seek
(i[, relative=false])def
setForwardOnly
(forward)def
setNumericalPrecisionPolicy
(precisionPolicy)def
size
()def
swap
(other)def
value
(name)def
value
(i)
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
QSqlQuery
encapsulates the functionality involved in creating, navigating and retrieving data from SQL queries which are executed on a QSqlDatabase
. It can be used to execute DML (data manipulation language) statements, such as SELECT
, INSERT
, UPDATE
and DELETE
, as well as DDL (data definition language) statements, such as CREATE
TABLE
. It can also be used to execute database-specific commands which are not standard SQL (e.g. SET DATESTYLE=ISO
for PostgreSQL).
Successfully executed SQL statements set the query’s state to active so that isActive()
returns true
. Otherwise the query’s state is set to inactive. In either case, when executing a new SQL statement, the query is positioned on an invalid record. An active query must be navigated to a valid record (so that isValid()
returns true
) before values can be retrieved.
For some databases, if an active query that is a SELECT
statement exists when you call commit()
or rollback()
, the commit or rollback will fail. See isActive()
for details.
Navigating records is performed with the following functions:
These functions allow the programmer to move forward, backward or arbitrarily through the records returned by the query. If you only need to move forward through the results (e.g., by using next()
), you can use setForwardOnly()
, which will save a significant amount of memory overhead and improve performance on some databases. Once an active query is positioned on a valid record, data can be retrieved using value()
. All data is transferred from the SQL backend using QVariants.
For example:
query = QSqlQuery("SELECT country FROM artist") while query.next(): country = query.value(0).toString() doSomething(country)
To access the data returned by a query, use value(int). Each field in the data returned by a SELECT
statement is accessed by passing the field’s position in the statement, starting from 0. This makes using SELECT *
queries inadvisable because the order of the fields returned is indeterminate.
For the sake of efficiency, there are no functions to access a field by name (unless you use prepared queries with names, as explained below). To convert a field name into an index, use record()
. indexOf()
, for example:
query = QSqlQuery("SELECT * FROM artist") fieldNo = query.record().indexOf("country") while query.next(): country = query.value(fieldNo).toString() doSomething(country)
QSqlQuery
supports prepared query execution and the binding of parameter values to placeholders. Some databases don’t support these features, so for those, Qt emulates the required functionality. For example, the Oracle and ODBC drivers have proper prepared query support, and Qt makes use of it; but for databases that don’t have this support, Qt implements the feature itself, e.g. by replacing placeholders with actual values when a query is executed. Use numRowsAffected()
to find out how many rows were affected by a non-SELECT
query, and size()
to find how many were retrieved by a SELECT
.
Oracle databases identify placeholders by using a colon-name syntax, e.g :name
. ODBC simply uses ?
characters. Qt supports both syntaxes, with the restriction that you can’t mix them in the same query.
You can retrieve the values of all the fields in a single variable using boundValues()
.
Note
Not all SQL operations support binding values. Refer to your database system’s documentation to check their availability.
Approaches to Binding Values#
Below we present the same example using each of the four different binding approaches, as well as one example of binding values to a stored procedure.
Named binding using named placeholders:
query = QSqlQuery() query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (:id, :forename, :surname)") query.bindValue(":id", 1001) query.bindValue(":forename", "Bart") query.bindValue(":surname", "Simpson") query.exec()
Positional binding using named placeholders:
query = QSqlQuery() query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (:id, :forename, :surname)") query.bindValue(0, 1001) query.bindValue(1, "Bart") query.bindValue(2, "Simpson") query.exec()
Binding values using positional placeholders (version 1):
query = QSqlQuery() query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (?, ?, ?)") query.bindValue(0, 1001) query.bindValue(1, "Bart") query.bindValue(2, "Simpson") query.exec()
Binding values using positional placeholders (version 2):
query = QSqlQuery() query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (?, ?, ?)") query.addBindValue(1001) query.addBindValue("Bart") query.addBindValue("Simpson") query.exec()
Binding values to a stored procedure:
This code calls a stored procedure called AsciiToInt()
, passing it a character through its in parameter, and taking its result in the out parameter.
query = QSqlQuery() query.prepare("CALL AsciiToInt(?, ?)") query.bindValue(0, "A") query.bindValue(1, 0, QSql.Out) query.exec() i = query.boundValue(1).toInt() # i is 65
Note that unbound parameters will retain their values.
Stored procedures that uses the return statement to return values, or return multiple result sets, are not fully supported. For specific details see SQL Database Drivers .
Warning
You must load the SQL driver and open the connection before a QSqlQuery
is created. Also, the connection must remain open while the query exists; otherwise, the behavior of QSqlQuery
is undefined.
See also
QSqlDatabase
QSqlQueryModel
QSqlTableModel
QVariant
- class PySide6.QtSql.QSqlQuery(r)#
PySide6.QtSql.QSqlQuery(db)
PySide6.QtSql.QSqlQuery(other)
Note
This constructor is deprecated.
PySide6.QtSql.QSqlQuery([query=””[, db=QSqlDatabase()]])
- Parameters:
query – str
other –
PySide6.QtSql.QSqlQuery
Constructs a QSqlQuery
object which uses the QSqlResult
result
to communicate with a database.
Constructs a QSqlQuery
object using the database db
. If db
is invalid, the application’s default database will be used.
See also
Constructs a copy of other
.
QSqlQuery
cannot be meaningfully copied. Prepared statements, bound values and so on will not work correctly, depending on your database driver (for instance, changing the copy will affect the original). Treat QSqlQuery
as a move-only type instead.
Constructs a QSqlQuery
object using the SQL query
and the database db
. If db
is not specified, or is invalid, the application’s default database is used. If query
is not an empty string, it will be executed.
See also
- PySide6.QtSql.QSqlQuery.BatchExecutionMode#
Constant
Description
QSqlQuery.ValuesAsRows
Updates multiple rows. Treats every entry in a QVariantList as a value for updating the next row.
QSqlQuery.ValuesAsColumns
Updates a single row. Treats every entry in a QVariantList as a single value of an array type.
- PySide6.QtSql.QSqlQuery.addBindValue(val[, type=QSql.In])#
- Parameters:
val – object
type – Combination of
QSql.ParamTypeFlag
Adds the value val
to the list of values when using positional value binding. The order of the addBindValue() calls determines which placeholder a value will be bound to in the prepared query. If paramType
is Out
or InOut
, the placeholder will be overwritten with data from the database after the exec()
call.
To bind a NULL value, use a null QVariant; for example, use QVariant(QMetaType::fromType<QString>())
if you are binding a string.
See also
- PySide6.QtSql.QSqlQuery.at()#
- Return type:
int
Returns the current internal position of the query. The first record is at position zero. If the position is invalid, the function returns BeforeFirstRow
or AfterLastRow
, which are special negative values.
See also
previous()
next()
first()
last()
seek()
isActive()
isValid()
- PySide6.QtSql.QSqlQuery.bindValue(pos, val[, type=QSql.In])#
- Parameters:
pos – int
val – object
type – Combination of
QSql.ParamTypeFlag
Set the placeholder in position pos
to be bound to value val
in the prepared statement. Field numbering starts at 0. If paramType
is Out
or InOut
, the placeholder will be overwritten with data from the database after the exec()
call.
- PySide6.QtSql.QSqlQuery.bindValue(placeholder, val[, type=QSql.In])
- Parameters:
placeholder – str
val – object
type – Combination of
QSql.ParamTypeFlag
Set the placeholder placeholder
to be bound to value val
in the prepared statement. Note that the placeholder mark (e.g :
) must be included when specifying the placeholder name. If paramType
is Out
or InOut
, the placeholder will be overwritten with data from the database after the exec()
call. In this case, sufficient space must be pre-allocated to store the result into.
To bind a NULL value, use a null QVariant; for example, use QVariant(QMetaType::fromType<QString>())
if you are binding a string.
- PySide6.QtSql.QSqlQuery.boundValue(placeholder)#
- Parameters:
placeholder – str
- Return type:
object
Returns the value for the placeholder
.
See also
- PySide6.QtSql.QSqlQuery.boundValue(pos)
- Parameters:
pos – int
- Return type:
object
Returns the value for the placeholder at position pos
.
See also
- PySide6.QtSql.QSqlQuery.boundValueName(pos)#
- Parameters:
pos – int
- Return type:
str
Returns the bound value name at position pos
.
The order of the list is in binding order, irrespective of whether named or positional binding is used.
See also
- PySide6.QtSql.QSqlQuery.boundValueNames()#
- Return type:
list of strings
Returns the names of all bound values.
The order of the list is in binding order, irrespective of whether named or positional binding is used.
See also
- PySide6.QtSql.QSqlQuery.boundValues()#
- Return type:
.list of QVariant
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns a list of bound values.
The order of the list is in binding order, irrespective of whether named or positional binding is used.
The bound values can be examined in the following way:
list = query.boundValues() for i in range(0, list.size()): print(i, ":", list.at(i).toString())
- PySide6.QtSql.QSqlQuery.clear()#
Clears the result set and releases any resources held by the query. Sets the query state to inactive. You should rarely if ever need to call this function.
- PySide6.QtSql.QSqlQuery.driver()#
- Return type:
Returns the database driver associated with the query.
- PySide6.QtSql.QSqlQuery.exec(query)#
- Parameters:
query – str
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Executes the SQL in query
. Returns true
and sets the query state to active
if the query was successful; otherwise returns false
. The query
string must use syntax appropriate for the SQL database being queried (for example, standard SQL).
After the query is executed, the query is positioned on an invalid record and must be navigated to a valid record before data values can be retrieved (for example, using next()
).
Note that the last error for this query is reset when exec()
is called.
For SQLite, the query string can contain only one statement at a time. If more than one statement is given, the function returns false
.
Example:
query = QSqlQuery() query.exec("INSERT INTO employee (id, name, salary) " "VALUES (1001, 'Thad Beaumont', 65000)")See also
isActive()
isValid()
next()
previous()
first()
last()
seek()
- PySide6.QtSql.QSqlQuery.exec()
- Return type:
bool
Executes a previously prepared SQL query. Returns true
if the query executed successfully; otherwise returns false
.
Note that the last error for this query is reset when exec() is called.
- PySide6.QtSql.QSqlQuery.execBatch([mode=QSqlQuery.BatchExecutionMode.ValuesAsRows])#
- Parameters:
mode –
BatchExecutionMode
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Executes a previously prepared SQL query in a batch. All the bound parameters have to be lists of variants. If the database doesn’t support batch executions, the driver will simulate it using conventional exec()
calls.
Returns true
if the query is executed successfully; otherwise returns false
.
Example:
q = QSqlQuery() q.prepare("insert into myTable values (?, ?)") ints = QVariantList() ints << 1 << 2 << 3 << 4 q.addBindValue(ints) names = QVariantList() names << "Harald" << "Boris" << "Trond" << QVariant(QMetaType.fromType<QString>()) q.addBindValue(names) if not q.execBatch(): print(q.lastError())
The example above inserts four new rows into myTable
:
1 Harald 2 Boris 3 Trond 4 NULL
To bind NULL values, a null QVariant of the relevant type has to be added to the bound QVariantList; for example, QVariant(QMetaType::fromType<QString>())
should be used if you are using strings.
Note
Every bound QVariantList must contain the same amount of variants.
Note
The type of the QVariants in a list must not change. For example, you cannot mix integer and string variants within a QVariantList.
The mode
parameter indicates how the bound QVariantList will be interpreted. If mode
is ValuesAsRows
, every variant within the QVariantList will be interpreted as a value for a new row. ValuesAsColumns
is a special case for the Oracle driver. In this mode, every entry within a QVariantList will be interpreted as array-value for an IN or OUT value within a stored procedure. Note that this will only work if the IN or OUT value is a table-type consisting of only one column of a basic type, for example TYPE myType IS TABLE OF VARCHAR(64) INDEX BY BINARY_INTEGER;
See also
- PySide6.QtSql.QSqlQuery.exec_()#
- Return type:
bool
- PySide6.QtSql.QSqlQuery.exec_(arg__1)
- Parameters:
arg__1 – str
- Return type:
bool
- PySide6.QtSql.QSqlQuery.executedQuery()#
- Return type:
str
Returns the last query that was successfully executed.
In most cases this function returns the same string as lastQuery()
. If a prepared query with placeholders is executed on a DBMS that does not support it, the preparation of this query is emulated. The placeholders in the original query are replaced with their bound values to form a new query. This function returns the modified query. It is mostly useful for debugging purposes.
See also
- PySide6.QtSql.QSqlQuery.finish()#
Instruct the database driver that no more data will be fetched from this query until it is re-executed. There is normally no need to call this function, but it may be helpful in order to free resources such as locks or cursors if you intend to re-use the query at a later time.
Sets the query to inactive. Bound values retain their values.
See also
- PySide6.QtSql.QSqlQuery.first()#
- Return type:
bool
Retrieves the first record in the result, if available, and positions the query on the retrieved record. Note that the result must be in the active
state and isSelect()
must return true before calling this function or it will do nothing and return false. Returns true
if successful. If unsuccessful the query position is set to an invalid position and false is returned.
See also
- PySide6.QtSql.QSqlQuery.isActive()#
- Return type:
bool
Returns true
if the query is active. An active QSqlQuery
is one that has been exec()'d
successfully but not yet finished with. When you are finished with an active query, you can make the query inactive by calling finish()
or clear()
, or you can delete the QSqlQuery
instance.
Note
Of particular interest is an active query that is a SELECT
statement. For some databases that support transactions, an active query that is a SELECT
statement can cause a commit()
or a rollback()
to fail, so before committing or rolling back, you should make your active SELECT
statement query inactive using one of the ways listed above.
See also
- PySide6.QtSql.QSqlQuery.isForwardOnly()#
- Return type:
bool
Returns true
if you can only scroll forward through a result set; otherwise returns false
.
See also
- PySide6.QtSql.QSqlQuery.isNull(field)#
- Parameters:
field – int
- Return type:
bool
Returns true
if the query is not active
, the query is not positioned on a valid record, there is no such field
, or the field
is null; otherwise false
. Note that for some drivers, isNull() will not return accurate information until after an attempt is made to retrieve data.
See also
- PySide6.QtSql.QSqlQuery.isNull(name)
- Parameters:
name – str
- Return type:
bool
This is an overloaded function.
Returns true
if there is no field with this name
; otherwise returns isNull
(int index) for the corresponding field index.
This overload is less efficient than isNull()
- PySide6.QtSql.QSqlQuery.isSelect()#
- Return type:
bool
Returns true
if the current query is a SELECT
statement; otherwise returns false
.
- PySide6.QtSql.QSqlQuery.isValid()#
- Return type:
bool
Returns true
if the query is currently positioned on a valid record; otherwise returns false
.
- PySide6.QtSql.QSqlQuery.last()#
- Return type:
bool
Retrieves the last record in the result, if available, and positions the query on the retrieved record. Note that the result must be in the active
state and isSelect()
must return true before calling this function or it will do nothing and return false. Returns true
if successful. If unsuccessful the query position is set to an invalid position and false is returned.
See also
- PySide6.QtSql.QSqlQuery.lastError()#
- Return type:
Returns error information about the last error (if any) that occurred with this query.
See also
- PySide6.QtSql.QSqlQuery.lastInsertId()#
- Return type:
object
Returns the object ID of the most recent inserted row if the database supports it. An invalid QVariant will be returned if the query did not insert any value or if the database does not report the id back. If more than one row was touched by the insert, the behavior is undefined.
For MySQL databases the row’s auto-increment field will be returned.
Note
For this function to work in PSQL, the table must contain OIDs, which may not have been created by default. Check the default_with_oids
configuration variable to be sure.
See also
- PySide6.QtSql.QSqlQuery.lastQuery()#
- Return type:
str
Returns the text of the current query being used, or an empty string if there is no current query text.
See also
- PySide6.QtSql.QSqlQuery.next()#
- Return type:
bool
Retrieves the next record in the result, if available, and positions the query on the retrieved record. Note that the result must be in the active
state and isSelect()
must return true before calling this function or it will do nothing and return false.
The following rules apply:
If the result is currently located before the first record, e.g. immediately after a query is executed, an attempt is made to retrieve the first record.
If the result is currently located after the last record, there is no change and false is returned.
If the result is located somewhere in the middle, an attempt is made to retrieve the next record.
If the record could not be retrieved, the result is positioned after the last record and false is returned. If the record is successfully retrieved, true is returned.
See also
- PySide6.QtSql.QSqlQuery.nextResult()#
- Return type:
bool
Discards the current result set and navigates to the next if available.
Some databases are capable of returning multiple result sets for stored procedures or SQL batches (a query strings that contains multiple statements). If multiple result sets are available after executing a query this function can be used to navigate to the next result set(s).
If a new result set is available this function will return true. The query will be repositioned on an invalid record in the new result set and must be navigated to a valid record before data values can be retrieved. If a new result set isn’t available the function returns false
and the query is set to inactive. In any case the old result set will be discarded.
When one of the statements is a non-select statement a count of affected rows may be available instead of a result set.
Note that some databases, i.e. Microsoft SQL Server, requires non-scrollable cursors when working with multiple result sets. Some databases may execute all statements at once while others may delay the execution until the result set is actually accessed, and some databases may have restrictions on which statements are allowed to be used in a SQL batch.
- PySide6.QtSql.QSqlQuery.numRowsAffected()#
- Return type:
int
Returns the number of rows affected by the result’s SQL statement, or -1 if it cannot be determined. Note that for SELECT
statements, the value is undefined; use size()
instead. If the query is not active
, -1 is returned.
See also
- PySide6.QtSql.QSqlQuery.numericalPrecisionPolicy()#
- Return type:
Returns the current precision policy.
See also
NumericalPrecisionPolicy
setNumericalPrecisionPolicy()
- PySide6.QtSql.QSqlQuery.prepare(query)#
- Parameters:
query – str
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Prepares the SQL query query
for execution. Returns true
if the query is prepared successfully; otherwise returns false
.
The query may contain placeholders for binding values. Both Oracle style colon-name (e.g., :surname
), and ODBC style (?
) placeholders are supported; but they cannot be mixed in the same query. See the Detailed Description
for examples.
Portability notes: Some databases choose to delay preparing a query until it is executed the first time. In this case, preparing a syntactically wrong query succeeds, but every consecutive exec()
will fail. When the database does not support named placeholders directly, the placeholder can only contain characters in the range [a-zA-Z0-9_].
For SQLite, the query string can contain only one statement at a time. If more than one statement is given, the function returns false
.
Example:
query = QSqlQuery() query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (:id, :forename, :surname)") query.bindValue(":id", 1001) query.bindValue(":forename", "Bart") query.bindValue(":surname", "Simpson") query.exec()See also
- PySide6.QtSql.QSqlQuery.previous()#
- Return type:
bool
Retrieves the previous record in the result, if available, and positions the query on the retrieved record. Note that the result must be in the active
state and isSelect()
must return true before calling this function or it will do nothing and return false.
The following rules apply:
If the result is currently located before the first record, there is no change and false is returned.
If the result is currently located after the last record, an attempt is made to retrieve the last record.
If the result is somewhere in the middle, an attempt is made to retrieve the previous record.
If the record could not be retrieved, the result is positioned before the first record and false is returned. If the record is successfully retrieved, true is returned.
- PySide6.QtSql.QSqlQuery.record()#
- Return type:
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns a QSqlRecord
containing the field information for the current query. If the query points to a valid row ( isValid()
returns true), the record is populated with the row’s values. An empty record is returned when there is no active query ( isActive()
returns false).
To retrieve values from a query, value()
should be used since its index-based lookup is faster.
In the following example, a SELECT * FROM
query is executed. Since the order of the columns is not defined, indexOf()
is used to obtain the index of a column.
q = QSqlQuery("select * from employees") rec = q.record() print("Number of columns: ", rec.count()) nameCol = rec.indexOf("name") # index of the field "name" while q.next(): print(q.value(nameCol).toString()) # output all namesSee also
- PySide6.QtSql.QSqlQuery.result()#
- Return type:
Returns the result associated with the query.
- PySide6.QtSql.QSqlQuery.seek(i[, relative=false])#
- Parameters:
i – int
relative – bool
- Return type:
bool
Retrieves the record at position index
, if available, and positions the query on the retrieved record. The first record is at position 0. Note that the query must be in an active
state and isSelect()
must return true before calling this function.
If relative
is false (the default), the following rules apply:
If
index
is negative, the result is positioned before the first record and false is returned.Otherwise, an attempt is made to move to the record at position
index
. If the record at positionindex
could not be retrieved, the result is positioned after the last record and false is returned. If the record is successfully retrieved, true is returned.
If relative
is true, the following rules apply:
If the result is currently positioned before the first record and:
index
is negative or zero, there is no change, and false is returned.
index
is positive, an attempt is made to position the result at absolute positionindex
- 1, following the sames rule for non relative seek, above.If the result is currently positioned after the last record and:
index
is positive or zero, there is no change, and false is returned.
index
is negative, an attempt is made to position the result atindex
+ 1 relative position from last record, following the rule below.If the result is currently located somewhere in the middle, and the relative offset
index
moves the result below zero, the result is positioned before the first record and false is returned.Otherwise, an attempt is made to move to the record
index
records ahead of the current record (orindex
records behind the current record ifindex
is negative). If the record at offsetindex
could not be retrieved, the result is positioned after the last record ifindex
>= 0, (or before the first record ifindex
is negative), and false is returned. If the record is successfully retrieved, true is returned.See also
- PySide6.QtSql.QSqlQuery.setForwardOnly(forward)#
- Parameters:
forward – bool
Sets forward only mode to forward
. If forward
is true, only next()
and seek()
with positive values, are allowed for navigating the results.
Forward only mode can be (depending on the driver) more memory efficient since results do not need to be cached. It will also improve performance on some databases. For this to be true, you must call setForwardOnly()
before the query is prepared or executed. Note that the constructor that takes a query and a database may execute the query.
Forward only mode is off by default.
Setting forward only to false is a suggestion to the database engine, which has the final say on whether a result set is forward only or scrollable. isForwardOnly()
will always return the correct status of the result set.
Note
Calling setForwardOnly after execution of the query will result in unexpected results at best, and crashes at worst.
Note
To make sure the forward-only query completed successfully, the application should check lastError()
for an error not only after executing the query, but also after navigating the query results.
Warning
PostgreSQL: While navigating the query results in forward-only mode, do not execute any other SQL command on the same database connection. This will cause the query results to be lost.
See also
- PySide6.QtSql.QSqlQuery.setNumericalPrecisionPolicy(precisionPolicy)#
- Parameters:
precisionPolicy –
NumericalPrecisionPolicy
Instruct the database driver to return numerical values with a precision specified by precisionPolicy
.
The Oracle driver, for example, can retrieve numerical values as strings to prevent the loss of precision. If high precision doesn’t matter, use this method to increase execution speed by bypassing string conversions.
Note: Drivers that don’t support fetching numerical values with low precision will ignore the precision policy. You can use hasFeature()
to find out whether a driver supports this feature.
Note: Setting the precision policy doesn’t affect the currently active query. Call exec(QString)
or prepare()
in order to activate the policy.
See also
NumericalPrecisionPolicy
numericalPrecisionPolicy()
- PySide6.QtSql.QSqlQuery.size()#
- Return type:
int
Returns the size of the result (number of rows returned), or -1 if the size cannot be determined or if the database does not support reporting information about query sizes. Note that for non-SELECT
statements ( isSelect()
returns false
), size() will return -1. If the query is not active ( isActive()
returns false
), -1 is returned.
To determine the number of rows affected by a non-SELECT
statement, use numRowsAffected()
.
See also
- PySide6.QtSql.QSqlQuery.swap(other)#
- Parameters:
other –
PySide6.QtSql.QSqlQuery
Swaps other
to this object. This operation is very fast and never fails.
- PySide6.QtSql.QSqlQuery.value(name)#
- Parameters:
name – str
- Return type:
object
This is an overloaded function.
Returns the value of the field called name
in the current record. If field name
does not exist an invalid variant is returned.
This overload is less efficient than value()
- PySide6.QtSql.QSqlQuery.value(i)
- Parameters:
i – int
- Return type:
object
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns the value of field index
in the current record.
The fields are numbered from left to right using the text of the SELECT
statement, e.g. in
forename, = SELECT()
field 0 is forename
and field 1 is surname
. Using SELECT *
is not recommended because the order of the fields in the query is undefined.
An invalid QVariant is returned if field index
does not exist, if the query is inactive, or if the query is positioned on an invalid record.
See also
previous()
next()
first()
last()
seek()
isActive()
isValid()