sql_auto_is_null

Description

sql_auto_is_null is used by some special drivers, such as ODBC, to control whether to obtain the value of the auto-increment column of the last inserted row.

Privilege requirements

• Query variables

  • Global level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE view (Oracle-compatible mode) or the information_schema.GLOBAL_VARIABLES view (MySQL-compatible mode) to obtain the value of the global system variable.

  • Session level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view (Oracle-compatible mode) or the information_schema.SESSION_VARIABLES view (MySQL-compatible mode) to obtain the value of the session system variable.

• Modify variables

  • Global level

    • sys tenant can directly modify the value of the global system variable.

    • MySQL user tenants must have the SUPER or ALTER SYSTEM privilege to modify the value of the global system variable.

    • Oracle user tenants must have the ALTER SYSTEM privilege to modify the value of the global system variable.

  • Session level

    sys tenant and all user tenants can directly modify the value of the session system variable.

Attributes

Usage

Assume that a table named t1 is created with the following statement:

obclient> CREATE TABLE t1 (auto_inc_column auto_increment, j int);

When the value of sql_auto_is_null is ON, the following two statements are equivalent:

obclient> SELECT * FROM t1 WHERE auto_inc_column is null;

obclient> SELECT * FROM t1 WHERE auto_inc_column = last_insert_id();

Examples

Allow the value of the auto-increment column of the last inserted row to be obtained by directly querying with the IS NULL condition.

• Session level

  obclient> SET sql_auto_is_null = on;
  

• Global level

  obclient> SET GLOBAL sql_auto_is_null = on;