Question

我在数据库中有几个表。我想找到哪些列（在哪些表中）没有任何值（列中的所有NULL）。我在下面的例子中，结果应该是

TestTable1 --> Var2
TestTable2 --> Variable1

我不知道如何创建这种查询。非常感谢您的帮助！

--create first table
create table dbo.TestTable1 (
sur_id int identity(1,1) not null primary key,
var1 int null,
var2 int null
)
go

--insert some values
insert into dbo.TestTable1 (var1) 
    select 1 union all select 2 union all select 3

--create second table
create table dbo.TestTable2 (
sur_id int identity(1,1) not null primary key,
variable1 int null,
variable2 int null
)

--and insert some values
insert into dbo.TestTable2 (variable2) 
    select 1 union all select 2 union all select 3

Answer 1

对于单个列，count(ColumnName)返回ColumName不为空的行数：

select  count(TheColumn)
from    YourTable

您可以为所有列生成查询。根据Martin的建议，您可以使用is_nullable = 1排除不能为null的列。例如：

select  'count(' + name + ') as ' + name + ', '
from    sys.columns
where   object_id = object_id('YourTable')
        and is_nullable = 1

如果表的数量很大，您可以以类似的方式为所有表生成查询。所有表的列表都在sys.tables。

Answer 2

更新....好吧，我对这个

有太多乐趣了 Proc接受两个参数，即搜索表和＆amp;适用的标准。你可以将本质和where子句传递给第二个参数。我编写了proc来将双引号解释为单引号....再次，这是基于原始开发人员的概念。

GO
/****** Object:  StoredProcedure [dbo].[SearchAllTables]    Script Date: 05/04/2011 14:29:48 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
alter PROC [dbo].[SearchAllTables2] ( @SEARCH_TABLE NVARCHAR(255), @CONDITION AS NVARCHAR(MAX) ) AS
BEGIN

-- Copyright © 2002 Narayana Vyas Kondreddi. All rights reserved.
-- Purpose: To search all columns of all tables for a given search string
-- Written by: Narayana Vyas Kondreddi -- Site: http://vyaskn.tripod.com
-- Tested on: SQL Server 7.0 and SQL Server 2000
-- Date modified: 28th July 2002 22:50 GMT
CREATE TABLE #Results (ColumnName nvarchar(370), ColumnValue nvarchar(3630))
SET NOCOUNT ON
DECLARE @TableName nvarchar(256), @ColumnName nvarchar(128), @SearchStr2 nvarchar(110), @COND_STR NVARCHAR(MAX)
SET @TableName = '' 
--SET @SearchStr2 = QUOTENAME('%' + @SearchStr + '%','''')
WHILE @TableName IS NOT NULL
BEGIN
SET @ColumnName = ''
SET @CONDITION = REPLACE(@CONDITION,'"','''')
SET @TableName =
(
SELECT MIN(QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME))
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_TYPE = 'BASE TABLE'
AND
QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME) > @TableName
AND OBJECTPROPERTY(
OBJECT_ID(
QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME)
), 'IsMSShipped'
) = 0 AND TABLE_NAME = @SEARCH_TABLE
) WHILE (@TableName IS NOT NULL) AND (@ColumnName IS NOT NULL) 
BEGIN SET @ColumnName = ( 
SELECT MIN(QUOTENAME(COLUMN_NAME)) 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_SCHEMA = PARSENAME(@TableName, 2) AND 
TABLE_NAME = PARSENAME(@TableName, 1) AND QUOTENAME(COLUMN_NAME) > @ColumnName ) 
IF @ColumnName IS NOT NULL 
BEGIN 
SET @COND_STR = REPLACE(@CONDITION,'''','"')
INSERT INTO #Results 
EXEC ( 'SELECT  DISTINCT ''' + @TableName + '.' + @ColumnName + ''',''' + @COND_STR + ''' AS CONDITION FROM ' + @TableName + ' (NOLOCK) ' + ' WHERE ' + @ColumnName + ' ' + @CONDITION)
PRINT ( 'SELECT  DISTINCT ''' + @TableName + '.' + @ColumnName + ''',''' + @COND_STR + ''' AS CONDITION FROM ' + @TableName + ' (NOLOCK) ' + ' WHERE ' + @ColumnName + ' ' + @CONDITION)
END 
END 
END 
    SELECT ColumnName, ColumnValue 
    FROM #Results 
END
GO
-- to execute

exec [SearchAllTables2] 'TABLENAME','LIKE "%DOUG%"' -- double quotes are automatically escaped to single quotes...

根据以下版权修改的原始代码....仅使用部分。

GO
/****** Object:  StoredProcedure [dbo].[SearchAllTables]    Script Date: 05/04/2011 14:29:48 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
alter PROC [dbo].[SearchAllTables2] ( @TABLE_NAME NVARCHAR(255) ) AS
BEGIN

-- Copyright © 2002 Narayana Vyas Kondreddi. All rights reserved.
-- Purpose: To search all columns of all tables for a given search string
-- Written by: Narayana Vyas Kondreddi -- Site: http://vyaskn.tripod.com
-- Tested on: SQL Server 7.0 and SQL Server 2000
-- Date modified: 28th July 2002 22:50 GMT
CREATE TABLE #Results (ColumnName nvarchar(370), ColumnValue nvarchar(3630))
SET NOCOUNT ON
DECLARE @TableName nvarchar(256), @ColumnName nvarchar(128), @SearchStr2 nvarchar(110)
SET @TableName = '' 
--SET @SearchStr2 = QUOTENAME('%' + @SearchStr + '%','''')
WHILE @TableName IS NOT NULL
BEGIN
SET @ColumnName = ''
SET @TableName =
(
SELECT MIN(QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME))
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_TYPE = 'BASE TABLE'
AND
QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME) > @TableName
AND OBJECTPROPERTY(
OBJECT_ID(
QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME)
), 'IsMSShipped'
) = 0 AND TABLE_NAME = @TABLE_NAME
) WHILE (@TableName IS NOT NULL) AND (@ColumnName IS NOT NULL) 
BEGIN SET @ColumnName = ( 
SELECT MIN(QUOTENAME(COLUMN_NAME)) 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_SCHEMA = PARSENAME(@TableName, 2) AND 
TABLE_NAME = PARSENAME(@TableName, 1) AND QUOTENAME(COLUMN_NAME) > @ColumnName ) 
IF @ColumnName IS NOT NULL 
BEGIN 
INSERT INTO #Results 
EXEC ( 'SELECT  DISTINCT ''' + @TableName + '.' + @ColumnName + ''', ''IS NULL'' FROM ' + @TableName + ' (NOLOCK) ' + ' WHERE ' + @ColumnName + ' IS NULL ')--LIKE ' + @SearchStr2 ) 
--PRINT ( 'SELECT  DISTINCT ''' + @TableName + '.' + @ColumnName + ''', ''IS NOT NULL'' FROM ' + @TableName + ' (NOLOCK) ' + ' WHERE  ' + @ColumnName + ' IS NOT NULL ')--LIKE ' + @SearchStr2 ) 
END 
END 
END 
    SELECT ColumnName, ColumnValue 
    FROM #Results 
END
GO
-- to execute

exec [SearchAllTables2] 'Master'

Answer 3

这是我编写的用于执行相同操作的脚本，它是一个两步的手动过程：

在SSMS中运行此脚本并选择“结果”窗格中的所有行：

SELECT
'SELECT
    COUNT( DISTINCT [' + COLUMN_NAME + ']) AS UniqueValues,
    ''' + TABLE_NAME + '.' + COLUMN_NAME + ''' AS ColumnName
FROM
    [' + TABLE_SCHEMA + '].[' + TABLE_NAME + ']

UNION ALL
'
FROM
    INFORMATION_SCHEMA.COLUMNS
ORDER BY
    TABLE_NAME,
    COLUMN_NAME

将结果粘贴到新的查询窗口中。滚动到最底部并删除尾随的UNION ALL语句。它看起来像这样：

SELECT   COUNT( DISTINCT [ModifiedByUserId]) AS UniqueValues,   'Inspections.ModifiedByUserId' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL  
SELECT   COUNT( DISTINCT [Notes]) AS UniqueValues,   'Inspections.Notes' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL  
SELECT   COUNT( DISTINCT [PublicPassword]) AS UniqueValues,   'Inspections.PublicPassword' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL  
SELECT   COUNT( DISTINCT [ShopId]) AS UniqueValues,   'Inspections.ShopId' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL  
SELECT   COUNT( DISTINCT [Status]) AS UniqueValues,   'Inspections.Status' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL  
SELECT   COUNT( DISTINCT [SupervisorUserId]) AS UniqueValues,   'Inspections.SupervisorUserId' AS ColumnName  FROM   [dbo].[Inspections]     UNION ALL

运行查询。在300列数据库上运行大约需要6分钟。它将更快或更慢，具体取决于使用的索引数量。

Answer 4

这非常有用，不会被放入一个方便的小系统proc中 - 特别是如果你刚刚继承了遗留数据库，并想知道你可以放弃或忽略哪些列。

/*
Show the count of not-null values in a table
*/
create proc sp_aaShowAllNullColumns @tableName varchar(255) as
begin
set nocount on

declare @sql nvarchar(4000)
declare @cols nvarchar(4000)
declare @tcols table( colbit nvarchar(255) )

insert @tcols
select 'count(' + name + ') as ' + name + ', ' as colbit
from    sys.columns
where   object_id = object_id(@tableName)
and is_nullable = 1 

select @cols = coalesce( @cols, ', ', '' ) + colbit from @tcols
select @cols = substring( @cols, 1, (len(@cols) - 1) )
select @cols = isnull( @cols, '' )

select @sql = 'select count(*) as Rows' + @cols + ' from ' + @tableName
exec sp_executeSql @sql

end
go

exec sys.sp_MS_marksystemobject 'sp_aaShowAllNullColumns'
go

use Bookshop
go
exec sp_aaShowAllNullColumns 'Books'
go

Answer 5

这是一个bash脚本，用于SQLite数据库中的所有非空表（或此类数据库中的所有指定表），标识all-NULL列。假定可以与SQLite数据库对话，则可以在您选择的编程语言中使用相同的技术。

#!/bin/bash

function help {
    cat <<EOF
Syntax: $0 databasefile [table ...]

If no tables are specified, then for each non-empty user table in the
specified SQLite database row, this script will emit the column names
of those columns in which all the values are NULL.  If any tables are
specified, only the specified tables are scanned.

The script is written to make it easy to modify the criteria and the output.

Thanks to SQL, two passes are required per table, and if no tables are
specified, an additional invocation of sqlite3 is required.

Column names are written in the form: tablename.columnname

Requirements:
  sqlite3 on the \$PATH

Options: 
 -v | --verbose :: emit additional information

EOF
}

while [ "$1" ]
do case "$1" in
      -h | --help | "" ) help
           exit
           ;;
      -v | --verbose ) VERBOSE=1
           shift
           ;;
      * ) break
      ;;
  esac
done

function verbose { if [ "$VERBOSE" ] ; then echo "$@" >&2 ; fi ; }

db="$1"
shift

if [ ! -s "$db" ] ; then echo "$0 : $db not found" ; exit ; fi

# To prevent loading ~/.sqliterc specify -init ""

# Global: db
function nullcolumns {
  local table="$1"
  local count column field nulls
  ( read count
    if [ -n "$count" ] ; then
        verbose "Row count for $table: $count"
    if [ "$count" -gt 0 ] ; then
          while read column ; do
          echo "SELECT '$column', * FROM
                  (SELECT COUNT(*) FROM $table WHERE '$column' IS NULL);"
          done |
          sqlite3 -readonly "$db" | while IFS="|" read field nulls ; do
            verbose $table.$field ... $nulls
            if [ "$nulls" -eq $count ] ; then echo "$table.$field" ; fi
          done
        else cat > /dev/null
        fi
    else cat > /dev/null
    fi ) < <(sqlite3 -readonly "$db" "select count(*) from '$table'; 
                                      select name from pragma_table_info( '$table' )")
}

if [ $# = 0 ] ; then
    sqlite3 -readonly "$db" .tables | while read table ; do
    nullcolumns "$table"
    done
else
    for table ; do
    nullcolumns "$table"
    done
fi

如何找到哪些列没有任何数据（所有值都为NULL）？

5 个答案: