44 lines
1.4 KiB
Markdown
44 lines
1.4 KiB
Markdown
关于 REPLACE INTO 语句
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REPLACE INTO 语句会判断行记录是否存在（根据主键索引或唯一索引判断）。如果不存在，则插入记录；如果存在，则删除已有记录，并插入新行记录。目标表建议有主键或者唯一索引，否则容易插入重复的记录。
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示例如下：
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```javascript
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obclient> CREATE TABLE t_replace(
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id number NOT NULL PRIMARY KEY
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, name varchar(10) NOT NULL
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, value number
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,gmt_create timestamp NOT NULL DEFAULT current_timestamp
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);
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Query OK, 0 rows affected (0.06 sec)
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obclient> REPLACE INTO t_replace values(1,'CN',2001, current_timestamp ());
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Query OK, 1 row affected (0.00 sec)
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obclient> REPLACE INTO t_replace
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SELECT id,name,value,gmt_create FROM t_insert;
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Query OK, 5 rows affected (0.00 sec)
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Records: 4 Duplicates: 1 Warnings: 0
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obclient> REPLACE INTO t_replace(id, name, value) values(6,'DE',20006);
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Query OK, 1 row affected (0.01 sec)
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obclient> select * from t_replace;
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+----+------+-------+---------------------+
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| id | name | value | gmt_create |
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+----+------+-------+---------------------+
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| 1 | CN | 10002 | 2020-04-03 18:05:45 |
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| 2 | US | 10103 | 2020-04-03 18:05:54 |
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| 3 | UK | 10003 | 2020-04-03 18:05:54 |
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| 4 | JP | 10005 | 2020-04-03 18:06:08 |
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| 6 | DE | 20006 | 2020-04-03 18:09:19 |
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+----+------+-------+---------------------+
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5 rows in set (0.01 sec)
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```
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