探討SQL利用INFORMATION_SCHEMA系統(tǒng)視圖如何獲取表的主外鍵信息
首先我們需要查詢列的信息,這需要用到[INFORMATION_SCHEMA].[COLUMNS]系統(tǒng)視圖來查詢數(shù)據(jù)列的信息,SQL 如下:
SELECT c.TABLE_SCHEMA ,
c.TABLE_NAME ,
c.COLUMN_NAME ,
c.DATA_TYPE ,
c.CHARACTER_MAXIMUM_LENGTH ,
c.COLUMN_DEFAULT ,
c.IS_NULLABLE ,
c.NUMERIC_PRECISION ,
c.NUMERIC_SCALE
FROM [INFORMATION_SCHEMA].[COLUMNS] c
WHERE TABLE_NAME = 'Address'
運(yùn)行結(jié)果如下:

我們都知道我們?cè)诙x列的時(shí)候一般的使用都是varchar(50)之類的信息,這里我們需要整合DATA_TYPE和CHARACTER_MAXIMUM_LENGTH信息,當(dāng)CHARACTER_MAXIMUM_LENGTH為-1時(shí)即使說沒有指定具體最大長(zhǎng)度,數(shù)據(jù)的指定長(zhǎng)度信息是max,而numeric需要整合NUMERIC_PRECISION、NUMERIC_SCALE信息。修改后的SQL如下:
SELECT c.TABLE_SCHEMA ,
c.TABLE_NAME ,
c.COLUMN_NAME ,
CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH <> -1
)
THEN c.DATA_TYPE + '('
+ CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH = -1
) THEN c.DATA_TYPE + '(max)'
WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
+ ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
ELSE c.DATA_TYPE
END AS DATA_TYPE ,
c.COLUMN_DEFAULT ,
c.IS_NULLABLE ,
c.COLUMN_DEFAULT
FROM [INFORMATION_SCHEMA].[COLUMNS] c
WHERE TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION
運(yùn)行結(jié)果如圖:

現(xiàn)在我們需要標(biāo)記這張表的那些列是主鍵,那些列是外鍵,要查詢表的主、外鍵信息需要用到[INFORMATION_SCHEMA].[TABLE_CONSTRAINTS]和[INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] 系統(tǒng)視圖
運(yùn)行結(jié)果如圖:

修改我們先前的SQL語(yǔ)句:
SELECT c.TABLE_SCHEMA ,
c.TABLE_NAME ,
c.COLUMN_NAME ,
CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH <> -1
)
THEN c.DATA_TYPE + '('
+ CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH = -1
) THEN c.DATA_TYPE + '(max)'
WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
+ ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
ELSE c.DATA_TYPE
END AS DATA_TYPE ,
c.COLUMN_DEFAULT ,
c.IS_NULLABLE ,
c.COLUMN_DEFAULT ,
CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN 'YES'
ELSE 'NO'
END AS IS_PRIMARY_KEY ,
CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN 'YES'
ELSE 'NO'
END AS IS_FOREIGN_KEY
FROM [INFORMATION_SCHEMA].[COLUMNS] c
LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
AND kcu.TABLE_NAME = c.TABLE_NAME
AND kcu.COLUMN_NAME = c.COLUMN_NAME
LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
WHERE c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION
運(yùn)行結(jié)果如圖:

現(xiàn)在我們已經(jīng)知道那些列是主鍵那些是外鍵,接下來的就是外鍵列所關(guān)聯(lián)的外檢表信息,這里需要用到[INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS]系統(tǒng)視圖,運(yùn)行該視圖如下:

所以修改我們的SQL如下:
SELECT c.TABLE_SCHEMA ,
c.TABLE_NAME ,
c.COLUMN_NAME ,
CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH <> -1
)
THEN c.DATA_TYPE + '('
+ CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH = -1
) THEN c.DATA_TYPE + '(max)'
WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
+ ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
ELSE c.DATA_TYPE
END AS DATA_TYPE ,
c.COLUMN_DEFAULT ,
c.IS_NULLABLE ,
c.COLUMN_DEFAULT ,
CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN 'YES'
ELSE 'NO'
END AS IS_PRIMARY_KEY ,
CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN 'YES'
ELSE 'NO'
END AS IS_FOREIGN_KEY,
fkcu.COLUMN_NAME AS FOREIGN_KEY,
fkcu.TABLE_NAME AS FOREIGN_TABLE
FROM [INFORMATION_SCHEMA].[COLUMNS] c
LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
AND kcu.TABLE_NAME = c.TABLE_NAME
AND kcu.COLUMN_NAME = c.COLUMN_NAME
LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
LEFT JOIN [INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS] fc ON kcu.CONSTRAINT_SCHEMA = fc.CONSTRAINT_SCHEMA
AND kcu.CONSTRAINT_NAME = fc.CONSTRAINT_NAME
LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] fkcu ON fkcu.CONSTRAINT_SCHEMA = fc.UNIQUE_CONSTRAINT_SCHEMA
AND fkcu.CONSTRAINT_NAME = fc.UNIQUE_CONSTRAINT_NAME
WHERE c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION
運(yùn)行結(jié)果如圖:

我們的查詢結(jié)果中顯示了太多的NULL,看著不怎么舒服,還有我們的表名應(yīng)該顯示一次就可以,修改SQL如下:
SELECT CASE WHEN c.ORDINAL_POSITION = 1
THEN c.TABLE_SCHEMA + '.' + c.TABLE_NAME
ELSE ''
END AS TABLE_NAME ,
c.COLUMN_NAME ,
CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH <> -1
)
THEN c.DATA_TYPE + '('
+ CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
OR CHARINDEX('binary', c.DATA_TYPE) > 0
)
AND c.CHARACTER_MAXIMUM_LENGTH = -1
) THEN c.DATA_TYPE + '(max)'
WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
+ ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
ELSE c.DATA_TYPE
END AS DATA_TYPE ,
ISNULL(c.COLUMN_DEFAULT, '') AS COLUMN_DEFAULT ,
CASE WHEN c.IS_NULLABLE = 'YES' THEN '√'
ELSE ''
END IS_NULLABLE ,
CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN '√'
ELSE ''
END AS IS_PRIMARY_KEY ,
CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN '√'
ELSE ''
END AS IS_FOREIGN_KEY ,
ISNULL(fkcu.COLUMN_NAME, '') AS FOREIGN_KEY ,
ISNULL(fkcu.TABLE_NAME, '') AS FOREIGN_TABLE
FROM [INFORMATION_SCHEMA].[COLUMNS] c
LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
AND kcu.TABLE_NAME = c.TABLE_NAME
AND kcu.COLUMN_NAME = c.COLUMN_NAME
LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
LEFT JOIN [INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS] fc ON kcu.CONSTRAINT_SCHEMA = fc.CONSTRAINT_SCHEMA
AND kcu.CONSTRAINT_NAME = fc.CONSTRAINT_NAME
LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] fkcu ON fkcu.CONSTRAINT_SCHEMA = fc.UNIQUE_CONSTRAINT_SCHEMA
AND fkcu.CONSTRAINT_NAME = fc.UNIQUE_CONSTRAINT_NAME
WHERE c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION
運(yùn)行結(jié)果如圖:

有不對(duì)的地方還請(qǐng)大家拍磚!
相關(guān)文章
mysql 5.6.14 win32 解壓縮版(免安裝)安裝配置教程
這篇文章主要介紹了mysql 5.6.14 win32 解壓縮版(免安裝)安裝配置教程,感興趣的小伙伴們可以參考一下2016-11-11MySQL實(shí)現(xiàn)批量插入測(cè)試數(shù)據(jù)的方式小結(jié)
在開發(fā)過程中我們不管是用來測(cè)試性能還是在生產(chǎn)環(huán)境中頁(yè)面展示好看一點(diǎn),?經(jīng)常需要一些測(cè)試數(shù)據(jù),?本文主要介紹了兩種常用的MySQL測(cè)試數(shù)據(jù)批量生成方式,希望對(duì)大家有所幫助2023-11-11關(guān)于Mysql查詢帶單引號(hào)及插入帶單引號(hào)字符串問題
本文主要介紹的是用mysql_real_escape_string對(duì)用戶提交的表單數(shù)據(jù)進(jìn)行轉(zhuǎn)義處理和通過addslashes以及mysql_escape_string這3個(gè)類似功能的函數(shù)用法區(qū)別2013-04-04mysql分頁(yè)時(shí)offset過大的Sql優(yōu)化經(jīng)驗(yàn)分享
mysql分頁(yè)是我們?cè)陂_發(fā)經(jīng)常遇到的一個(gè)功能,最近在實(shí)現(xiàn)該功能的時(shí)候遇到一個(gè)問題,所以這篇文章主要給大家介紹了關(guān)于mysql分頁(yè)時(shí)offset過大的Sql優(yōu)化經(jīng)驗(yàn),文中介紹的非常詳細(xì),對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,需要的朋友們下面跟著小編來一起看看吧。2017-08-08.Net Core導(dǎo)入千萬級(jí)數(shù)據(jù)至Mysql的步驟
最近在工作中,涉及到一個(gè)數(shù)據(jù)遷移功能,從一個(gè)txt文本文件導(dǎo)入到MySQL功能。數(shù)據(jù)遷移,在互聯(lián)網(wǎng)企業(yè)可以說經(jīng)常碰到,而且涉及到千萬級(jí)、億級(jí)的數(shù)據(jù)量是很常見的。今天我們就來談?wù)凪ySQL怎么高性能插入千萬級(jí)的數(shù)據(jù)。2021-05-05MySQL創(chuàng)建和刪除數(shù)據(jù)庫(kù)的命令及相關(guān)PHP腳本的操作方法
這篇文章主要介紹了MySQL創(chuàng)建和刪除數(shù)據(jù)庫(kù)的命令及相關(guān)PHP腳本的操作方法,這里主要講述Linux中在mysqladmin下的命令操作,需要的朋友可以參考下2015-11-11MYSQL每隔10分鐘進(jìn)行分組統(tǒng)計(jì)的實(shí)現(xiàn)方法
這篇文章主要給大家介紹了如何利用MYSQL實(shí)現(xiàn)每隔10分鐘進(jìn)行分組統(tǒng)計(jì)的方法,文中給出了詳細(xì)的示例代碼,相信對(duì)大家的理解和學(xué)習(xí)具有一定的參考借鑒價(jià)值,有需要的朋友們下面來一起看看吧。2016-12-12Mysql查詢條件判斷是否包含字符串的方法實(shí)現(xiàn)
本文主要介紹了Mysql查詢條件判斷是否包含字符串的方法實(shí)現(xiàn),主要包括like,locate,postion,instr,find_in_set這幾種方法,具有一定的參考價(jià)值,感興趣的可以了解一下2023-10-10MySQL/Postgrsql 詳細(xì)講解如何用ODBC接口訪問MySQL指南
2008-01-01