Oracle - 如何使用动态绑定参数定义动态SQL？

Question

我在Oracle数据库中有这个简单的搜索存储过程，并且想要动态地为我的绑定变量指定值。例如，如果只指定了employee no，那么我的sql只有一个绑定变量，但是如果指定了employee no和name，那么我的sql将有两个绑定变量。我怎样才能在“USING”条款中实现这一点？

CREATE OR REPLACE PROCEDURE SP_EMPLOYEE_SEARCH_TEST 
    (IN_EMP_NO              IN VARCHAR2,
    IN_EMP_NAME              IN VARCHAR2,
    OUT_C_SEARCH_RESULT           OUT sys_refcursor)  
IS
SQL_QUERY VARCHAR2(500);

BEGIN

SQL_QUERY := 'SELECT * FROM EMPLOYEE WHERE ' ;

IF (IN_EMP_NO IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || 'EMPLOYEE_NO = :1 ';
END IF;

IF (IN_EMP_NAME IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || ' AND EMPLOYEE_NAME = :2';
END IF;

dbms_output.put_line(SQL_QUERY);

OPEN OUT_C_SEARCH_RESULT FOR
    SQL_QUERY USING <<How to define dynamically>>;   

END SP_EMPLOYEE_SEARCH_TEST;

Answer 1

只需传递它们但改变你的动态部分：

IF (IN_EMP_NO IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || 'EMPLOYEE_NO = :1 ';
ELSE
    SQL_QUERY :=  SQL_QUERY || ':1 IS NULL ';
END IF;

IF (IN_EMP_NAME IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || ' AND EMPLOYEE_NAME = :2';
ELSE
    SQL_QUERY :=  SQL_QUERY || ' AND :2 IS NULL';
END IF;

这样查询仍具有相同数量的绑定。

您也可以像这样重写查询：

SELECT * FROM EMPLOYEE
 WHERE EMPLOYEE_NO = NVL(:1, EMPLOYEE_NO)
   AND EMPLOYEE_NAME = NVL(:2, EMPLOYEE_NAME)

当绑定值为null时，它仍然使用相同数量的参数并获得所需的结果。

Answer 2

如果你有最大值2-3个可选参数我会采用手动方式：

IF IN_EMP_NO IS NULL AND IN_EMP_NAME IS NULL THEN
    OPEN OUT_C_SEARCH_RESULT FOR SQL_QUERY;
ELSIF IN_EMP_NO IS NOT NULL AND IN_EMP_NAME IS NULL THEN
    OPEN OUT_C_SEARCH_RESULT FOR SQL_QUERY USING IN_EMP_NO;
ELSIF IN_EMP_NO IS NULL AND IN_EMP_NAME IS NOT NULL THEN
    OPEN OUT_C_SEARCH_RESULT FOR SQL_QUERY USING IN_EMP_NAME;
ELSIF IN_EMP_NO IS NOT NULL AND IN_EMP_NAME IS NOT NULL THEN
    OPEN OUT_C_SEARCH_RESULT FOR SQL_QUERY USING IN_EMP_NO, IN_EMP_NAME;
END IF;

或者像这样构建你的查询：

SQL_QUERY := 'SELECT * FROM EMPLOYEE WHERE ' ;
SQL_QUERY :=  SQL_QUERY || ' (EMPLOYEE_NO = :1 OR :2 IS NULL)';
SQL_QUERY :=  SQL_QUERY || ' AND (EMPLOYEE_NAME = :3 OR :4 IS NULL)';
OPEN OUT_C_SEARCH_RESULT FOR
   SQL_QUERY USING IN_EMP_NO, IN_EMP_NO, IN_EMP_NAME, IN_EMP_NAME;  

否则，如果你想拥有更多的灵活性，那么看看DBMS_SQL包。一个有效的例子就是这个：

CREATE OR REPLACE PROCEDURE SP_EMPLOYEE_SEARCH_TEST 
    (IN_EMP_NO              IN VARCHAR2,
    IN_EMP_NAME              IN VARCHAR2,
    OUT_C_SEARCH_RESULT           OUT sys_refcursor)  
IS

SQL_QUERY VARCHAR2(500);
cur INTEGER;
ret NUMBER;
bind BOOLEAN := FALSE;

BEGIN


IF (IN_EMP_NO IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || 'AND EMPLOYEE_NO = :p1 '; -- note the space at the end!
    bind := TRUE;
END IF;

IF (IN_EMP_NAME IS NOT NULL) THEN
    SQL_QUERY :=  SQL_QUERY || 'AND EMPLOYEE_NAME = :p2 '; 
    bind := TRUE;
END IF;

IF bind then
   SQL_QUERY := 'SELECT * FROM EMPLOYEE '||REGEXP_REPLACE(SQL_QUERY, '^AND', 'WHERE');    
ELSE
   SQL_QUERY := 'SELECT * FROM EMPLOYEE';
END IF:
dbms_output.put_line(SQL_QUERY);

cur := dbms_sql.open_cursor;
DBMS_SQL.PARSE(cur, SQL_QUERY, DBMS_SQL.NATIVE);

IF (IN_EMP_NO IS NOT NULL) THEN
    DBMS_SQL.BIND_VARIABLE(cur, ':p1', IN_EMP_NO);
END IF;    
IF (IN_EMP_NAME IS NOT NULL) THEN
    DBMS_SQL.BIND_VARIABLE(cur, ':p2', IN_EMP_NAME);
END IF;

ret := DBMS_SQL.EXECUTE(cur);
OUT_C_SEARCH_RESULT := DBMS_SQL.TO_REFCURSOR(cur);


END SP_EMPLOYEE_SEARCH_TEST;