我有一个包含近 200 列的临时表。我需要知道每列的最大长度，以便我可以纠正警告“字符串或二进制数据将被截断”。现在我不能提到像
这样的所有列select max(len(col1)),max(len(col2))....,,, from #tableA
现在如何获取所有列的最大长度？
【问题讨论】：
标签： sql sql-server multiple-columns
是的，您可以将 INFORMATION_SCHEMA.COLUMNS 用于任何数据库。
为您的数据库名称添加前缀。在您的情况下使用 tempdb.INFORMATION_SCHEMA.COLUMNS
SELECT COLUMN_NAME,
CHARACTER_MAXIMUM_LENGTH,
NUMERIC_PRECISION
FROM tempdb.INFORMATION_SCHEMA.COLUMNS
WHERE table_name like '%tableA%'
【讨论】：
我遇到了同样的问题，found the code below（来自the site 的完整复制/粘贴）对我有用。不幸的是，我不得不经历几次数据加载迭代来找出每一列是罪魁祸首，但最终能够解决所有问题：
/**************************************
SQL to get max length of values in every table column.
This SQL queries the specified table to get the max length
of all the values in every column.
To work, load all the incoming data into a "permanent" temporary table
where every column is defined as a varchar(max).
Then run this script against that "permanent" temporary table, comparing
the results against the original table's schema to see what column, and
then what record(s), is/are causing the issue.
Example, if the max length of a value in one of the columns is 270,
but your original table's schema is varchar(255), obviously either
the original table's schema will have to be altered or the data corrected.
Code from: http://cc.davelozinski.com
**************************************/
--The table we'll be performing this query on to get the lengths of every column.
--Default is dbo schema. Change as appropriate for your table.
DECLARE @TableName VARCHAR(200) = 'Your table name to query'
,@SchemaName VARCHAR(200) = 'dbo'
DECLARE @MaxLengthDefault INT
,@Column VARCHAR(50)
,@MaxLength INT
,@MaxLengthString VARCHAR(10)
,@ColumnID INT
,@MaxColumnID INT
,@Command VARCHAR(2000)
CREATE TABLE #Temp (
column_name VARCHAR(50)
,max_length INT
,max_length_default INT
)
SELECT @ColumnID = min(b.[column_id])
,@MaxColumnID = max(b.[column_id])
FROM sys.tables a
INNER JOIN sys.columns b on a.[object_id] = b.[object_id]
WHERE a.[name] = @TableName
and SCHEMA_NAME(a.[schema_id]) = @SchemaName
--SELECT @ColumnID, @MaxColumnID
WHILE(@ColumnID <= @MaxColumnID)
BEGIN
SET @Column = null
SELECT @Column = b.[name]
,@MaxLengthDefault = b.[max_length]
FROM sys.tables a
INNER JOIN sys.columns b on a.[object_id] = b.[object_id]
WHERE a.[name] = @TableName
and SCHEMA_NAME(a.[schema_id]) = @SchemaName
and b.[column_id] = @ColumnID
--SELECT @Column, @MaxLengthDefault
IF ( @Column is not null )
BEGIN
SET @Command = 'INSERT INTO #Temp(column_name, max_length, max_length_default)
SELECT ''' + @Column + '''
,MAX(LEN(CAST([' + @Column + '] as VARCHAR(8000))))
,' + CAST(@MaxLengthDefault as VARCHAR(5)) +
' FROM [' + @SchemaName + '].[' + @TableName + ']
WHERE [' + @Column + '] IS NOT NULL'
--SELECT @Command
EXEC(@Command)
END
SET @ColumnID = @ColumnID + 1
END
SELECT * FROM #Temp
DROP TABLE #Temp
【讨论】：
试试这个：
SELECT COLUMN_NAME,CHARACTER_MAXIMUM_LENGTH,NUMERIC_PRECISION
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = N'TableName'
请在此处找到更多信息 How can I get column names from a table in SQL Server?
【讨论】：
要获取temp table 的所有列的最大长度，您可以将查询编写为：
select name,max_length
from tempdb.sys.columns
where object_id = object_id('tempdb..#Temp');
【讨论】：