SELECT A.*, B.FUND_CODE AS FUND_CODE, B.FUND_FULLNAME AS Fund_Fullname FROM BSP_SYS_ATTACH A,BSP_FUND_BASE B WHERE A.ENTITY_ID=B.FUND_ID /* 此处A.ENTITY_ID的类型为VARCHAR; B.FUND_ID的类型为NUMBER; 两者类型不匹配所以报错。 */
SELECT A.*, B.FUND_CODE AS FUND_CODE, B.FUND_FULLNAME AS Fund_Fullname FROM BSP_SYS_ATTACH A,BSP_FUND_BASE B WHERE A.ENTITY_ID=TO_CHAR(B.FUND_ID) /* 类型转换函数to_char() */
将日期型转换为字符串TO_CHAR()
SELECT TO_CHAR (SYSDATE, 'YYYY-MM-DD HH24:MI:SS AM') FROM DUAL
将数字型转换为字符串TO_CHAR()
SELECT TO_CHAR(123.45678,'$99999.999') FROM DUAL;
将字符换转换为日期TO_DATE()
SELECT TO_DATE ('20100913', 'YYYY-MM-DD') FROM DUAL;
将字符串转换为数字TO_NUMBER()
SELECT TO_NUMBER('01') FROM DUAL;