PL/SQL Language Elements, 18 of 52

EXECUTE IMMEDIATE Statement

The EXECUTE IMMEDIATE statement prepares (parses) and immediately executes a dynamic SQL statement or anonymous PL/SQL block. For more information, see Chapter 11.

Syntax

Text description of execute_immediate_statement.gif follows

Text description of the illustration execute_immediate_statement.gif

Keyword and Parameter Description

bind_argument

This can be an expression whose value is passed to the dynamic SQL statement or PL/SQL block, or it can be a variable that stores a value returned by the dynamic SQL statement or PL/SQL block.

define_variable_name

This identifies a variable that stores a selected column value.

dynamic_string

This is a string literal, variable, or expression that represents a SQL statement or PL/SQL block.

INTO ...

Used only for single-row queries, this clause specifies the variables or record into which column values are retrieved. For each value retrieved by the query, there must be a corresponding, type-compatible variable or field in the INTO clause.

record_name

This identifies a user-defined or %ROWTYPE record that stores a selected row.

RETURNING INTO ...

Used only for DML statements that have a RETURNING clause (without a BULK COLLECT clause), this clause specifies the bind variables into which column values are returned. For each value returned by the DML statement, there must be a corresponding, type-compatible variable in the RETURNING INTO clause.

USING ...

This clause specifies a list of input and/or output bind arguments. If you do not specify a parameter mode, it defaults to IN.

Usage Notes

Except for multi-row queries, the dynamic string can contain any SQL statement (without the terminator) or any PL/SQL block (with the terminator). The string can also contain placeholders for bind arguments. However, you cannot use bind arguments to pass the names of schema objects to a dynamic SQL statement.

You can place all bind arguments in the USING clause. The default parameter mode is IN. For DML statements that have a RETURNING clause, you can place OUT arguments in the RETURNING INTO clause without specifying the parameter mode, which, by definition, is OUT. If you use both the USING clause and the RETURNING INTO clause, the USING clause can contain only IN arguments.

At run time, bind arguments replace corresponding placeholders in the dynamic string. So, every placeholder must be associated with a bind argument in the USING clause and/or RETURNING INTO clause. You can use numeric, character, and string literals as bind arguments, but you cannot use Boolean literals (TRUE, FALSE, and NULL). To pass nulls to the dynamic string, you must use a workaround. See "Passing Nulls".

Dynamic SQL supports all the SQL datatypes. So, for example, define variables and bind arguments can be collections, LOBs, instances of an object type, and refs. As a rule, dynamic SQL does not support PL/SQL-specific types. So, for example, define variables and bind arguments cannot be Booleans or index-by tables. The only exception is that a PL/SQL record can appear in the INTO clause.

You can execute a dynamic SQL statement repeatedly using new values for the bind arguments. However, you incur some overhead because EXECUTE IMMEDIATE re-prepares the dynamic string before every execution.

Examples

The following PL/SQL block contains several examples of dynamic SQL:

DECLARE
   sql_stmt    VARCHAR2(200);
   plsql_block VARCHAR2(500);
   emp_id      NUMBER(4) := 7566;
   salary      NUMBER(7,2);
   dept_id     NUMBER(2) := 50;
   dept_name   VARCHAR2(14) := 'PERSONNEL';
   location    VARCHAR2(13) := 'DALLAS';
   emp_rec     emp%ROWTYPE;
BEGIN
   EXECUTE IMMEDIATE 'CREATE TABLE bonus (id NUMBER, amt NUMBER)';

   sql_stmt := 'INSERT INTO dept VALUES (:1, :2, :3)';
   EXECUTE IMMEDIATE sql_stmt USING dept_id, dept_name, location;

   sql_stmt := 'SELECT * FROM emp WHERE empno = :id';
   EXECUTE IMMEDIATE sql_stmt INTO emp_rec USING emp_id;

   plsql_block := 'BEGIN emp_pkg.raise_salary(:id, :amt); END;';
   EXECUTE IMMEDIATE plsql_block USING 7788, 500;

   sql_stmt := 'UPDATE emp SET sal = 2000 WHERE empno = :1
      RETURNING sal INTO :2';
   EXECUTE IMMEDIATE sql_stmt USING emp_id RETURNING INTO salary;

   EXECUTE IMMEDIATE 'DELETE FROM dept WHERE deptno = :num'
      USING dept_id;

   EXECUTE IMMEDIATE 'ALTER SESSION SET SQL_TRACE TRUE';
END;