sql-server - 将所有 VARCHAR 列更改为 NVARCHAR

Question

我的数据库中有大约 200 列 VARCHAR无法存储卢比符号的类型。现在我必须更改 VARCHAR 中所有列的数据类型至 NVARCHAR .

谁能告诉我实现这一目标的捷径？为什么VARCHAR支持英镑符号而不是卢比符号？我问是因为我必须将英镑符号更改为卢比符号。

Answer 1

您可以使用 ff 查询查看所有列、它们的数据类型和它们所属的表:

SELECT 
    t.name AS table_name,
    c.name AS column_name,
    tp.name AS data_type,
    c.max_length,
    c.is_nullable
FROM sys.tables AS t
INNER JOIN sys.columns c 
    ON t.OBJECT_ID = c.OBJECT_ID
INNER JOIN sys.types tp
    ON tp.user_type_id = c.user_type_id
WHERE tp.name = 'varchar'

从上面的查询中，您要生成一个动态 sql，它将更改您所有的 VARCHAR列到 NVARCHAR .

DECLARE @sql AS VARCHAR(MAX) = ''

SELECT @sql = @sql 
    + 'ALTER TABLE ' + table_name 
    + ' ALTER COLUMN ' + column_name + ' NVARCHAR(' 
        + CASE WHEN max_length <> - 1 THEN CAST(max_length AS VARCHAR(10))  ELSE 'MAX' END + ')'
        + CASE WHEN is_nullable = 1 THEN ' NULL' ELSE '' END
        + ';' + CHAR(10)
FROM (
    SELECT 
        t.name AS table_name,
        c.name AS column_name,
        tp.name AS data_type,
        c.max_length,
        c.is_nullable
    FROM sys.tables AS t
    INNER JOIN sys.columns c 
        ON t.OBJECT_ID = c.OBJECT_ID
    INNER JOIN sys.types tp
        ON tp.user_type_id = c.user_type_id
    WHERE tp.name = 'varchar'
)t

PRINT @sql
EXEC(@sql)