What's the difference between these two update SQL statements in Oracle
First:
UPDATE t1
SET col1 = 'Y'
WHERE EXISTS (SELECT *
FROM t2
WHERE t1.p1 = t2.p1
AND t1.p2 = t2.p2
AND t2.col3 = 'a'
AND t1.p1 = 'b'
AND t1.p2 = 'c')
Second:
UPDATE t1
SET col1 = 'Y'
WHERE EXISTS (SELECT *
FROM t2
WHERE t1.p1 = t2.p1
AND t1.p2 = t2.p2
AND t2.col3 = 'a')
AND t1.p1 = 'b'
AND t1.p2 = 'c'
完全没有区别-它们具有相同的含义
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