Question

我能够在Oracle和MSSQL中使用MERGE语句。现在我必须使用MYSQL。 MYSQL是否有类似的声明来合并数据。

假设我有两张桌子：

create table source
(
 col1 bigint not null primary key auto_increment,
 col2 varchar(100),
 col3 varchar(50)
 created datetime
)

create table destination
(
 col1 bigint not null primary key auto_increment,
 col2 varchar(100),
 col3 varchar(50)
 created datetime 
)

现在我希望移动来自＆＃34; source＆＃34;的所有数据。到＆＃34;目的地＆＃34;。如果记录已存在于＆＃34;目的地＆＃34;按键我需要更新，否则我需要插入。

在MSSQL中我使用以下MERGE语句，类似可以在ORACLE中使用：

MERGE destination AS TARGET
USING(SELECT * FROM source WHERE col2 like '%GDA%') AS SOURCE
ON
(TARGET.col1 = SOURCE.col1)
WHEN MATCHED THEN
UPDATE SET TARGET.col2 = SOURCE.col2,
           TARGET.col3 = SOURCE.col3
WHEN NOT MATCHED THEN
INSERT INTO
(col2,col3,created)
VALUES
(
SOURCE.col2,
SOURCE.col3,
GETDATE()
)OUTPUT $action INTO $tableAction;

WITH mergeCounts AS
(
SELECT COUNT(*) cnt,
     MergeAction
  FROM @tableAction
 GROUP BY MergeAction
) 
SELECT @Inserted = (SELECT ISNULL(cnt,0) FROM mergeCounts WHERE MergeAction = 'INSERT'),
     @Updated = (SELECT ISNULL(cnt,0) FROM mergeCounts WHERE MergeAction = 'UPDATE'),
     @Deleted = (SELECT ISNULL(cnt,0) FROM mergeCounts WHERE MergeAction = 'DELETE')

所以我在这里更新记录（如果存在）并插入新记录。在MERGE语句之后，我还可以计算插入了多少条记录，更新了......

是否可以在MYSQL中实现这样的实现？

Answer 1

Mysql具有insert ... on duplicate key update ...语法。像这样使用它：

insert into destination(col1, col2, col3, created) 
  select * 
    from source
  on duplicate key update
    col2 = values(col2),
    col3 = values(col3),
    created = values(created);

demo here

获取受影响的行数，然后运行select row_count()

如何在MYSQL中合并记录

1 个答案: