如果插入一條記錄到數據庫裏面,總是要先查詢該條記錄是否存在,不存在則插入,如果存在則放棄或者給出提示信息,
能否用一條記錄來實現呢?
我找到了DB2和oracle的sql用法:
DB2:
MERGE INTO schema.table as T USING TABLE(VALUES('keyValue')) S(keyName) ON (T.keyName=S.keyName) WHEN NOT MATCHED THEN INSERT (keyName, contentlName) values(?,?);
oracle:
INSERT INTO schema.table (keyName, contentlName) select ?,? from dual where not exists (select * from schema.table where keyName=?);
這裏都用到的是prepareStatement.
也許你用到了mysql,或者sqlServer,思路基本都一樣.
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