Question

我有一个sql表，它有两列id和name。我有20个名字的列表，我需要编写一个查询，检查名称是否存在插入之前。

有没有更好的方法来做到这一点，而不是只有下面的查询20次，但有不同的名称（我需要在t-sql中这样做）：

IF NOT EXISTS(SELECT* 
              FROM   mytable 
              WHERE  name = 'Dan') 
  BEGIN 
      INSERT INTO mytable 
                  (name) 
      VALUES     ('dan') 
  END

Answer 1

我认为你可以使用合并声明：

MERGE INTO myTable AS Target
USING (VALUES ('name1'),('name2'),('...')) AS source (NAME)
ON Target.NAME = Source.NAME
WHEN NOT MATCHED BY TARGET THEN
INSERT (NAME) VALUES (name)

Answer 2

INSERT INTO MyTable (Name)
SELECT  NewNames.Name
FROM    ( VALUES ('Name1'), ('Name2'), ('Name3') ) AS NewNames (Name)
WHERE   NOT EXISTS ( SELECT 1
                     FROM   MyTable AS MT
                     WHERE  MT.Name = NewNames.Name );

Answer 3

您可以使用NOT EXISTS

过滤值

INSERT INTO myTable (
    Name
)
SELECT DISTINCT
    Name
FROM (
        VALUES ('Name 1'),
               ('Name 2')
    ) AS NewNames(Name)
WHERE
    NOT EXISTS (SELECT 1 FROM TargetTable WHERE myTable.Name = NewNames.Name)

如果您的新名称在另一个表中，您可以更改上面的选择查询。

请注意，必须使用DISTINCT关键字来过滤掉源数据中的重复项。

Answer 4

我会使用insert执行此操作：

with names as (
      select 'Dan' as name union all
      select 'name2' union all
      . . .
     )
insert into myTable(name)
    select distinct name
    from myTable
    where not exists (select 1 from mytable t2 where t2.name = t.name);

注意：您可能希望在mytable(name)上创建唯一索引，以便数据库检查重复项。

Answer 5

INSERT IGNORE INTO myTable (column1, column2) VALUES (val1, val2),(val3,val4),(val5,val6);

INSERT IGNORE将允许跳过重复值

Answer 6

未经测试，因此可能会出现一些小错误：

merge into mytable x
using (
    values ('name1')
         , ('name2')
         , ...
         , ('namen')
) as y (name)
    on x.name = y.name
when not matched then 
    insert (name)
    values (y.name)

Answer 7

INSERT INTO MyTable (Name)
SELECT Name FROM
(
    VALUES ('Name 1'),
           ('Name 2')
) AS Names(Name)
WHERE Name NOT IN
(
    SELECT Name FROM MyTable
)

如果不存在，Sql会插入多行

7 个答案: