오라클 Oracle EXECUTE IMMEDIATE tips

http://www.dba-oracle.com/t_oracle_execute_immediate.htm

The syntax for the Oracle EXECUTE IMMEDIATE statement as follows:

EXECUTE IMMEDIATE <SQL or SPL Commands>
  [INTO <variable list>]
  [USING <bind variable list>];

Quotes and execute immediate

When executing a string variable that contains quotes it is important to "escape" the quote marks.

On 10g and beyond you can "escape" the quotes with two single quotes or a "q" and curly brackets:

For example, this "execute immediate" escapes the quotes with a q'{xxxxxxxx}'

sqlstring := q'{insert into x values( ' || i || ')}';

execute immediate sqlstring;

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As we see, the Oracle EXECUTE IMMEDIATE statement can be used to execute dynamic SQL statements. Oracle EXECUTE IMMEDIATE can also build up statements to execute operations in which you do not know the table names, or other properties.

The Oracle EXECUTE IMMEDIATE statement has a wide variety of uses. For more information on Oracle EXECUTE IMMEDIATE see the following links:

Oracle EXECUTE IMMEDIATE - Dynamic SQL and Bulk Operations

Oracle EXECUTE IMMEDIATE - How to execute dynamic PL/SQL procedure calls

Late Binding and Runtime Binding in PL/SQL

In its most basic form, Oracle EXECUTE IMMEDIATE takes only a single parameter and that is a command string.

Here is an example showing how to use dynamic DDL to create, drop and re-create a table:

BEGIN
EXECUTE IMMEDIATE 'create table abcd (efgh NUMBER)';
EXECUTE IMMEDIATE 'drop table abcd';
EXECUTE IMMEDIATE 'create table abcd (efgh VARCHAR2(10))';
END;

You can use this method to execute any DDL.

More than likely, you will use dynamic SQL to execute DML commands more often than DDL. With dynamic SQL you can issue inserts, updates and deletes just as you can with static SQL:

BEGIN
EXECUTE IMMEDIATE 'INSERT INTO abcd (efgh) VALUES (:text_string)' 
USING 'ijkl';
EXECUTE IMMEDIATE 'INSERT INTO abcd (efgh) VALUES (:text_string)' 
USING 'mnop';
EXECUTE IMMEDIATE 'UPDATE abcd ' ||
'SET efgh = :text_string WHERE efgh = :second_string' 
USING 'qrst', 'mnop';
EXECUTE IMMEDIATE 'DELETE FROM abcd ' ||
'WHERE efgh = :text_string '
USING 'qrst';

END;

As useful as DDL and DML are, a database is not very useful if you can't get your data out. You can also use execute immediate to select your data back out.

DECLARE
v_data abcd.efgh%TYPE;

v_data_row abcd%ROWTYPE;

BEGIN

EXECUTE IMMEDIATE 'SELECT efgh FROM abcd WHERE efgh = :text_string' 
INTO v_data
USING 'ijkl';

DBMS_OUTPUT.PUT_LINE( 'Column Variable: ' || v_data );

EXECUTE IMMEDIATE 'SELECT * FROM abcd WHERE efgh = :text_string' 
INTO v_data_row
USING 'ijkl';

DBMS_OUTPUT.PUT_LINE( 'Row Variable: ' || v_data_row.efgh );

END;

INFO: Column Variable: ijkl
INFO: Row Variable: ijkl

Note:  There are cases where you can get an insufficient privileges error when executing a stored procedure that contains execute immediate statements.

execute immediate causes insufficient privileges over a database link