EXECUTE IMMEDIATE
EXECUTE IMMEDIATE combines the basic functions of the PREPARE and EXECUTE statements. It can be used to prepare and execute SQL statements that contain neither variables nor parameter markers.
The EXECUTE IMMEDIATE statement:
- Prepares an executable form of an SQL statement from a character string form of the statement
- Executes the SQL statement
Invocation
This statement can only be embedded in an application program, SQL function, SQL procedure, or trigger. It is an executable statement that cannot be dynamically prepared. It must not be specified in Java™.
Authorization
If a global variable is referenced in a statement, the privileges held by the authorization ID of the statement must include at least one of the following:
- For the global variable identified in the statement,
- The READ privilege on the global variable, and
- The system authority *EXECUTE on the library containing the global variable
Database administrator authority
The authorization rules are those defined for the SQL statement specified by EXECUTE IMMEDIATE. For example, see INSERT for the authorization rules that apply when an INSERT statement is executed using EXECUTE IMMEDIATE.
The authorization ID of the statement is the run-time authorization ID unless DYNUSRPRF(*OWNER) was specified on the CRTSQLxxx command when the program was created. For more information, see Authorization IDs and authorization names.
Syntax
Description
- variable
- Identifies a variable that must be declared in accordance with the rules for declaring character-string or Unicode graphic variables. An indicator variable must not be specified.
- expression
- An expression of
the type described in Expressions, that
does not include an aggregate function or column name. It must return
a value that is a character string or a Unicode graphic string. If a variable is specified in the expression it
must not have a CCSID of 65535.1
The value of the identified variable or expression
is called a statement string.
The statement string must be one of the following SQL statements:3
| ALTER | LABEL | SET CURRENT DEGREE |
| CALL | LOCK TABLE | SET CURRENT IMPLICIT XMLPARSE OPTION |
| COMMENT | MERGE | SET ENCRYPTION PASSWORD |
| COMMIT | REFRESH TABLE | SET PATH |
| Compound (dynamic) |
RELEASE SAVEPOINT | SET SCHEMA |
| CREATE | RENAME | SET SESSION AUTHORIZATION |
| DECLARE GLOBAL TEMPORARY TABLE | REVOKE | SET TRANSACTION |
| DELETE | ROLLBACK | SET variable2 |
| DROP | SAVEPOINT | TRANSFER OWNERSHIP |
| GRANT | SET CURRENT DEBUG MODE | TRUNCATE |
| INSERT | SET CURRENT DECFLOAT ROUNDING MODE | UPDATE |
The statement string must not:
- Begin with EXEC SQL.
- End with END-EXEC or a semicolon.
- Include references to variables. Global variables
are allowed.
- Include parameter markers.
When an EXECUTE IMMEDIATE statement is executed, the specified statement string is parsed and checked for errors. If the SQL statement is not valid, it is not executed and the error condition that prevents its execution is reported in the stand-alone SQLSTATE and SQLCODE. If the SQL statement is valid, but an error occurs during its execution, that error condition is reported in the stand-alone SQLSTATE and SQLCODE. Additional information about the error can be retrieved from the SQL Diagnostics Area (or the SQLCA).
Note
Performance considerations: If the same SQL statement is to be executed more than once, it is more efficient to use the PREPARE and EXECUTE statements rather than the EXECUTE IMMEDIATE statement.
Example
Use C to execute the SQL statement in the variable Qstring.
void main ()
{
EXEC SQL BEGIN DECLARE SECTION END-EXEC.
char Qstring[100] = "INSERT INTO WORK_TABLE SELECT * FROM EMPPROJACT
WHERE ACTNO >= 100";
EXEC SQL END DECLARE SECTION END-EXEC.
EXEC SQL INCLUDE SQLCA;
.
.
.
EXEC SQL EXECUTE IMMEDIATE :Qstring;
return;
}