现在有表A1,A2,A3和B
A1,A2,A3的结构完全一致,只不过使用了不同的seq做主键
CONDITION1,CONDITION2,CONDITION3也是一样的现在问
SQL1:
SELECT (SELECT ### FROM A1 WHERE CONDITION1
UNION
SELECT ### FROM A2 WHERE CONDITION2
UNION
SELECT ### FROM A3 WHERE CONDITION3)A
LEFT JOIN B
WHERE .....SQL2:
SELECT (SELECT ### FROM A1
UNION
SELECT ### FROM A2
UNION
SELECT ### FROM A3)A
LEFT JOIN B
WHERE CONDITION1 AND .....SQL3:
SELECT ### FROM A1 WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A2 WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A3 WHERE CONDITION1 AND .....哪种办法效率最好,CONDITION1里只有 LIKE '%VALUE%' 和 ='VALUE' 两种
A1,A2,A3的结构完全一致,只不过使用了不同的seq做主键
CONDITION1,CONDITION2,CONDITION3也是一样的现在问
SQL1:
SELECT (SELECT ### FROM A1 WHERE CONDITION1
UNION
SELECT ### FROM A2 WHERE CONDITION2
UNION
SELECT ### FROM A3 WHERE CONDITION3)A
LEFT JOIN B
WHERE .....SQL2:
SELECT (SELECT ### FROM A1
UNION
SELECT ### FROM A2
UNION
SELECT ### FROM A3)A
LEFT JOIN B
WHERE CONDITION1 AND .....SQL3:
SELECT ### FROM A1 WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A2 WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A3 WHERE CONDITION1 AND .....哪种办法效率最好,CONDITION1里只有 LIKE '%VALUE%' 和 ='VALUE' 两种
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SELECT ### FROM A1 LEFT JOIN B WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A2 LEFT JOIN B WHERE CONDITION1 AND .....
UNION
SELECT ### FROM A3 LEFT JOIN B WHERE CONDITION1 AND .....
忘了写表连了