drop table if exists address_book;这句SQL语句是什么意思我备份的SQL语句中有这么一行,

drop table if exists address_book;这句SQL语句是什么意思我备份的SQL语句中有这么一行, 数据库中if OBJECT_ID ('dbo.table_test_6_1','u') is not null drop table table_test_6_1判断是否存在该 exists // IF EXISTS (SELECT name FROM m MySQL DROP Table 用法如题 IF OBJECT_ID(N'STUDENT') IS NOT NULL DROP TABLE STUDENT GO 这是T-SQL语句,IF OBJECT_ID(N'STUDENT') IS NOT NULLDROP TABLE STUDENTGO这是T-SQL语句, drop in or drop by?please_____ my house if you come by this way.drop by?drop in?drop off? if exists (select 1 from #tmp_dj_xsg212 WHERE shangplx LIKE '%冷%' if exists 括号后的条件如何写 If you were a tear drop Drop in if you come my way. 在数据库中IF 和 IF EXISTS 有什么区别IF (条件)BEGIN语句快END和下面有什么区别?IF EXISTS (条件)BEGIN语句快END Drop drop drop if not exists (SELECT * From TA_ARTIFICER Where ARTID = @Artid)是什么意思?为什么要用到if not exists呢?在什么时候要用到 if not exists（）?它的作用是什么? SQL 请高手帮忙看一下以下语法哪里有错误.USE tempdb;IF OBJECT_ID('dbo.Arrays') IS NOT NULL DROP TABLE dbo.Arrays;CREATE TABLE dbo.Arrays(arrid VARCHAR(10) NOT NULL PRIMARY KEY,array VARCHAR(8000) NOT NULL)GOINSERT INTO Arrays(arrid,arr if we have time,we will____for dinner A.drop B.drop in C.have D./