preparing sql dynamically in oracle stored procedure - sql

Question

I have 3 input parameters,based on values of each input parameter i have to prepare the SQL in procedure dynamically. I am doing below way but it is failing, if the parameter value is null,then i have to exclude that from the where clause.
IN Parameters:
empid in varchar2 || empname IN varchar2 || empsal IN varchar2
SELECT
EMP_NAME
INTO
V_EMP_NAME
FROM
EMPLOYEE
WHERE
( EMP_ID = EMPID
OR ( EMP_ID IS NULL
AND EMPID IS NULL ) )
AND ( EMP_NAME = EMPNAME
OR ( EMP_NAME IS NULL
AND EMPNAME IS NULL ) )
AND ( EMP_SAL = EMPSAL
OR ( EMP_SAL IS NULL
AND EMPSAL IS NULL ) );
After updates i modified the query like below,it is compiled but giving run time errors saying that ORA-00933: SQL command not properly ended on just before EXECUTE IMMEDIATE
V_SQL :='SELECT EMP_NAME INTO V_empname FROM employee WHERE ';
BEGIN
IF(EMPID IS NOT NULL) THEN
V_SQL := V_SQL || ' emp_id='||EMPID;
END IF;
IF(EMPNAME IS NOT NULL) THEN
V_SQL := V_SQL || ' AND emp_name='||EMPNAME;
END IF;
IF(V_empsalIS NOT NULL) THEN
V_SQL := V_SQL || ' AND emp_sal='||empsal;
V_SQL := V_SQL ||' AND ACTIVE =''Y''' ;
END IF;
EXECUTE IMMEDIATE V_SQL;
EXCEPTION
WHEN NO_DATA_FOUND THEN
V_check:= '' ;
END;

Answer 1

Here you are another alternative:
V_SQL_WHERE := null;
V_SQL :='SELECT EMP_NAME INTO V_empname FROM employee';
BEGIN
IF(EMPID IS NOT NULL) THEN
V_SQL_WHERE := V_SQL_WHERE || ' emp_id='||EMPID;
END IF;
IF(EMPNAME IS NOT NULL) THEN
IF (V_SQL_WHERE is not null) THEN
V_SQL_WHERE := V_SQL_WHERE || ' AND ';
END IF;
V_SQL_WHERE := V_SQL_WHERE || ' emp_name='||EMPNAME;
END IF;
IF(V_empsalIS NOT NULL) THEN
IF (V_SQL_WHERE is not null) THEN
V_SQL_WHERE := V_SQL_WHERE || ' AND ';
END IF;
V_SQL_WHERE := V_SQL_WHERE || ' emp_sal=' || empsal;
V_SQL_WHERE := V_SQL_WHERE || ' AND ACTIVE =''Y''' ;
END IF;
IF (V_SQL_WHERE is not null) then
V_SQL := V_SQL || ' WHERE ' || V_SQL_WHERE;
end if;
EXECUTE IMMEDIATE V_SQL;
EXCEPTION
WHEN NO_DATA_FOUND THEN
V_check:= '' ;
END;

Answer 2

Something like this: (Not tested, but just an idea)
BEGIN
IF EMPID IS NOT NULL
THEN
CLAUSE1 := 'EMP_ID = EMPID';
ELSE
CLAUSE1 := '1=1';
END IF;
IF EMPNAME IS NOT NULL
THEN
CLAUSE2 := 'EMP_NAME = EMPNAME';
ELSE
CLAUSE2 := '1=1';
END IF;
IF EMPSAL IS NOT NULL
THEN
CLAUSE3 := 'EMP_SAL = EMPSAL';
ELSE
CLAUSE3 := '1=1';
END IF;
IF ( EMPSAL IS NULL
AND EMPNAME IS NULL
AND EMPID IS NOT NULL )
THEN
CLAUSE1 := '1=0';
CLAUSE2 := '1=0';
CLAUSE3 := '1=0';
END IF;
QUERY_STR :=
' SELECT EMP_NAME INTO V_EMP_NAME FROM EMPLOYEE WHERE'
|| CLAUSE1
|| ' AND '
|| CLAUSE2
|| ' AND '
|| CLAUSE3;
END;

Answer 3

You can create one from scratch, including if's and elses, or you can use a package called plsql-utils, the SQL_BUILDER_PKG. It does the whole work for you.
Have a look on SQL utilities
http://code.google.com/p/plsql-utils/
Eg:
declare
l_my_query sql_builder_pkg.t_query;
l_sql varchar2(32000);
begin
sql_builder_pkg.add_select (l_my_query, 'ename');
sql_builder_pkg.add_select (l_my_query, 'sal');
sql_builder_pkg.add_select (l_my_query, 'deptno');
sql_builder_pkg.add_from (l_my_query, 'emp');
sql_builder_pkg.add_where (l_my_query, 'ename = :p_ename');
sql_builder_pkg.add_where (l_my_query, 'sal > :p_sal');
l_sql := sql_builder_pkg.get_sql (l_my_query);
dbms_output.put_line (l_sql);
end;
I used it in one project and it was a good tool.