下面是一个示例的IF NOT EXISTS写法: ```sql IF NOT EXISTS(SELECT * FROM table_name WHERE condition) BEGIN --在这里执行相关的操作 END ``` 在上面的示例中,`table_name`表示要检查的表名,`condition`表示要应用的条件。如果通过SELECT语句查询不到符合条件的记录,则会执行BEGIN和END之间的操作。 请注意...
1.介绍 if not exists 即如果不存在,if exists 即如果存在 2.使用 a.判断数据库不存在时 if not exists(select * from sys.databases where name = ‘database_name’) b.判断表不存在时 if not exists (select * from sysobjects where id = object_id(‘table_name’) and OBJECTPROPERTY(id, ’IsU...
if not exists (SELECT 1 FROM [t_Table] where [fName] = '张三') insert into [t_Table] ([fName]) values ('张三'); sqlite语法: 代码如下: insert into [t_Table] ([fName]) select '张三' where not exists (SELECT 1 FROM [t_Table] where [fName] = '张三'); 更多信息请查看IT技...
CREATE TABLE IF NOT EXISTS table_name ( column1 datatype1, column2 datatype2, ... ); 1. 2. 3. 4. 5. 6. 7. 2. 替换`table_name`为你想要创建的表名,`column1`、`column2`为表的列名,`datatype1`、`datatype2`为列的数据类型。 3. 保存文件,以`.sql`为后缀,例如`create_table.sql`...
IF (v_tbl_cnt=0)THEN--table not existsexecuteimmediate'create table ...';--create tableENDIF;selectcount(1)intov_seq_cntfromSYSIBM.SYSSEQUENCESwhereowner='your_schema'andname='your_sequence'; IF (v_seq_cnt=0)THEN--sequence not existsexecuteimmediate'create sequence ...';--create sequenc...
select @sidtmp = sid from @sidtable where id=@i while @j<@id2count+1 begin select @cidtmp = cid from @id2coursetable where id=@j select @result=count(*) from grade where sid = @sidtmp and cid = @cidtmp if(@result = 0) ...
end if; execute immediate 'create table Account ( AccountID nvarchar2(50) primary key, AccountName nvarchar2(50) )'; dbms_output.put_line('成功创建表!'); end; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 1:隐式游标法 SQL%NOTFOUND SQL%FOUND ...
So in short I insert new records with new "Appointment no" into "table 1" and the duplicate appointment no which already exist in table 1 , into table 1_copy. I could figure out the insert into if NOT EXISTS PART but am struggling to capture the dups and insert into...
select * from B where exists(select cc from A where cc=B.cc) -->效率低,用到了A表上cc列的索引。 2、not in 和not exists not in 逻辑上不完全等同于not exists,如果你误用了not in,小心你的程序存在致命的BUG,请看下面的例子: create table #t1(c1 int,c2 int); ...
1、创建一个临时表，IFOBJECT_ID('tempdb..#tmp1') IS NOT NULL DROP TABLE #tmp1; CREATE TABLE #tmp1(Col1 varchar(50)，Col2 varchar(200));。2、往临时表中插入几行测试数据，用于exists使用insert into #tmp1(Col1, Col2) values('Code1', '1');insert into #tmp1(Col1, Col...