Question

我有我的sqlserver脚本，用于测试索引中是否存在列，如果是，则删除索引。但是当我运行它时，它会显示错误：

Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

当我更改IN by EXISTS时，会返回此错误：

Incorrect syntax near the keyword 'EXISTS'.

我的脚本是：

while (SELECT COLUMN_NAME FROM ( SELECT SC.name as TABLE_SCHEMA,
                                                 t.name as TABLE_NAME,
                                                 ind.name as indexName,
                                                 ind.type_desc AS type_Index,
                                  SUBSTRING(( SELECT ', ' + AC.name
                           FROM DATA.sys.[tables] AS T
                           INNER JOIN DATA.sys.[indexes] I   ON T.[object_id] = I.[object_id]
                           INNER JOIN DATA.sys.[index_columns] IC ON I.[object_id] = IC.[object_id] AND I.[index_id] = IC.[index_id]
                           INNER JOIN DATA.sys.[all_columns] AC ON T.[object_id] = AC.[object_id] AND IC.[column_id] = AC.[column_id] 
                           WHERE Ind.[object_id] = I.[object_id] AND Ind.index_id = I.index_id AND IC.is_included_column = 0
                           ORDER BY IC.key_ordinal
                     FOR    XML PATH('')), 2, 8000) AS COLUMN_NAME
              FROM DATA.sys.indexes ind 
              INNER JOIN DATA.sys.index_columns ic ON  ind.object_id = ic.object_id and ind.index_id = ic.index_id 
              INNER JOIN DATA.sys.columns col ON ic.object_id = col.object_id and ic.column_id = col.column_id 
              INNER JOIN DATA.sys.tables t ON ind.object_id = t.object_id
              INNER JOIN DATA.sys.schemas SC ON t.schema_id =  SC.schema_id
              WHERE SC.name ='SSCI_SALR') as SubQ
GROUP BY COLUMN_NAME) IN ( SELECT * FROM INFORMATION_SCHEMA.COLUMNS
                            WHERE DATA_TYPE IN ('nchar', 'nvarchar')
                            and TABLE_SCHEMA IN ('SSCI_SALR', 'SYSTEM_SALR'))
BEGIN

print 'test okkkkk';
IF EXISTS (SELECT *  FROM DATA.SYS.INDEXES WHERE NAME = 'indexName')
Drop Index indexName On DATA.Table_Name;

SELECT
    AlterSql = CONCAT('ALTER TABLE ', TABLE_SCHEMA, '.', TABLE_NAME, ' ALTER COLUMN ', COLUMN_NAME, 
       ' ', SUBSTRING(DATA_TYPE, 2, LEN(DATA_TYPE)), '(', CHARACTER_MAXIMUM_LENGTH, ') ', 
       CASE IS_NULLABLE 
       WHEN 'YES' THEN 'NULL'
       WHEN 'NO' THEN 'NOT NULL'
       ELSE 'ERROR'
       END,
       CHAR(13),
       CHAR(10), 'GO')     
  , *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE DATA_TYPE IN ('nchar', 'nvarchar')
and TABLE_SCHEMA IN ('SSCI_SALR', 'SYSTEM_SALR')

END;

GO

有人可以告诉我哪里是我的错？谢谢。

Answer 1

第一，使用IF条件而不是While来执行逻辑运算。此外，您的查询是错误的，我这样修改了它;

IF(EXISTS(SELECT COLUMN_NAME FROM ( SELECT SC.name as TABLE_SCHEMA,
                                                 t.name as TABLE_NAME,
                                                 ind.name as indexName,
                                                 ind.type_desc AS type_Index,
                                  SUBSTRING(( SELECT ', ' + AC.name
                           FROM DATA.sys.[tables] AS T
                           INNER JOIN DATA.sys.[indexes] I   ON T.[object_id] = I.[object_id]
                           INNER JOIN DATA.sys.[index_columns] IC ON I.[object_id] = IC.[object_id] AND I.[index_id] = IC.[index_id]
                           INNER JOIN DATA.sys.[all_columns] AC ON T.[object_id] = AC.[object_id] AND IC.[column_id] = AC.[column_id] 
                           WHERE ind.[object_id] = I.[object_id] AND ind.index_id = I.index_id AND IC.is_included_column = 0
                           ORDER BY IC.key_ordinal
                     FOR    XML PATH('')), 2, 8000) AS COLUMN_NAME
              FROM DATA.sys.indexes ind 
              INNER JOIN DATA.sys.index_columns ic ON  ind.object_id = ic.object_id and ind.index_id = ic.index_id 
              INNER JOIN DATA.sys.columns col ON ic.object_id = col.object_id and ic.column_id = col.column_id 
              INNER JOIN DATA.sys.tables t ON ind.object_id = t.object_id
              INNER JOIN DATA.sys.schemas SC ON t.schema_id =  SC.schema_id
              WHERE SC.name ='SSCI_SALR') as SubQ
              WHERE COLUMN_NAME IN ( SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS
                            WHERE DATA_TYPE IN ('nchar', 'nvarchar')
                            and TABLE_SCHEMA IN ('SSCI_SALR', 'SYSTEM_SALR'))
GROUP BY COLUMN_NAME))
begin
   print 'ok'
end

在sqlserver中不正确的EXISTS

1 个答案: