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在sqlserver中,常用的系統(tǒng)表有sysobjects,syscolumns, 這兩個(gè)可以判斷表是否存在,字段是否存在,可以滿足一些需求的查詢.但項(xiàng)目有需求,需要對(duì)比兩張表的字段類型和長(zhǎng)度是否相等,主要針對(duì)varchar,nvarchar類型的字段.這個(gè)時(shí)候就需要使用到另外一個(gè)視圖 information_schema.columns . 該視圖記錄著表的列的詳細(xì)信息.

以下為查詢PROPOSAL表的列名相關(guān)信息

select  t2.TABLE_NAME,t2.COLUMN_NAME,t2.data_type,t2.character_maximum_length,* FROM information_schema.columns t2where table_name='proposal'

截圖如下圖

兩表對(duì)比查詢(proposal_history,proposal)

SELECT a.TABLE_NAME AS 表1,b.TABLE_NAME AS 表2,a.COLUMN_NAME AS 列名,        a.DATA_TYPE AS 表1字段類型,b.DATA_TYPE AS 表2字段類型,        a.CHARACTER_MAXIMUM_LENGTH AS 表1字段長(zhǎng)度,        b.CHARACTER_MAXIMUM_LENGTH AS 表2字段長(zhǎng)度 FROM     (select  t1.TABLE_NAME,t1.COLUMN_NAME,t1.data_type,ISNULL(t1.character_maximum_length,-1) AS CHARACTER_MAXIMUM_LENGTH    from information_schema.columns t1    where table_name='proposal_history')ALEFT JOIN     (select  t2.TABLE_NAME,t2.COLUMN_NAME,t2.data_type,ISNULL(t2.character_maximum_length,-1) AS CHARACTER_MAXIMUM_LENGTH    from information_schema.columns t2    where table_name='proposal')BON a.COLUMN_NAME = b.COLUMN_NAMEWHERE (b.COLUMN_NAME IS NULL OR a.DATA_TYPE != b.DATA_TYPE OR a.CHARACTER_MAXIMUM_LENGTH ! = b.CHARACTER_MAXIMUM_LENGTH);

查詢結(jié)果

以上表示 proposal_history 表比 proposal 多id,prp_version,create_time 三個(gè)字段.,并且兩表的etitle字段類型不一致,分別為varchar,nvarchar. 調(diào)換兩表位置,可以反著查.