使用查詢生成現(xiàn)有表的CREATE腳本

許多用戶尋求一種方法來生成SQL Server中現(xiàn)有表的CREATE腳本，尤其是在這些表不包含任何數(shù)據(jù)的情況下。為此，理解查詢系統(tǒng)表（如sys.tables）的機(jī)制至關(guān)重要。

用于生成CREATE Table腳本的查詢

以下查詢演示了如何為數(shù)據(jù)庫中任何現(xiàn)有表生成CREATE腳本：

DECLARE @table_name SYSNAME;
DECLARE 
      @object_name SYSNAME,
      @object_id INT;

SELECT 
      @object_name = '[' + s.name + '].[' + o.name + ']',
      @object_id = o.[object_id]
FROM sys.objects o WITH (NOWAIT)
JOIN sys.schemas s WITH (NOWAIT) ON o.[schema_id] = s.[schema_id]
WHERE s.name + '.' + o.name = @table_name
    AND o.[type] = 'U'
    AND o.is_ms_shipped = 0;

DECLARE @SQL NVARCHAR(MAX) = '';

;WITH index_column AS 
(
    SELECT 
          ic.[object_id],
          ic.index_id,
          ic.is_descending_key,
          ic.is_included_column,
          c.name
    FROM sys.index_columns ic WITH (NOWAIT)
    JOIN sys.columns c WITH (NOWAIT) ON ic.[object_id] = c.[object_id] AND ic.column_id = c.column_id
    WHERE ic.[object_id] = @object_id
),
fk_columns AS 
(
     SELECT 
          k.constraint_object_id,
          cname = c.name,
          rcname = rc.name
    FROM sys.foreign_key_columns k WITH (NOWAIT)
    JOIN sys.columns rc WITH (NOWAIT) ON rc.[object_id] = k.referenced_object_id AND rc.column_id = k.referenced_column_id 
    JOIN sys.columns c WITH (NOWAIT) ON c.[object_id] = k.parent_object_id AND c.column_id = k.parent_column_id
    WHERE k.parent_object_id = @object_id
)
SELECT @SQL = 'CREATE TABLE ' + @object_name + CHAR(13) + '(' + CHAR(13) + STUFF((
    SELECT CHAR(9) + ', [' + c.name + '] ' + 
        CASE WHEN c.is_computed = 1
            THEN 'AS ' + cc.[definition] 
            ELSE UPPER(tp.name) + 
                CASE WHEN tp.name IN ('varchar', 'char', 'varbinary', 'binary', 'text')
                       THEN '(' + CASE WHEN c.max_length = -1 THEN 'MAX' ELSE CAST(c.max_length AS VARCHAR(5)) END + ')'
                     WHEN tp.name IN ('nvarchar', 'nchar', 'ntext')
                       THEN '(' + CASE WHEN c.max_length = -1 THEN 'MAX' ELSE CAST(c.max_length / 2 AS VARCHAR(5)) END + ')'
                     WHEN tp.name IN ('datetime2', 'time2', 'datetimeoffset') 
                       THEN '(' + CAST(c.scale AS VARCHAR(5)) + ')'
                    WHEN tp.name IN ('decimal', 'numeric')
                       THEN '(' + CAST(c.[precision] AS VARCHAR(5)) + ',' + CAST(c.scale AS VARCHAR(5)) + ')'
                    ELSE ''
                END +
                CASE WHEN c.collation_name IS NOT NULL THEN ' COLLATE ' + c.collation_name ELSE '' END +
                CASE WHEN c.is_nullable = 1 THEN ' NULL' ELSE ' NOT NULL' END +
                CASE WHEN dc.[definition] IS NOT NULL THEN ' DEFAULT' + dc.[definition] ELSE '' END + 
                CASE WHEN ic.is_identity = 1 THEN ' IDENTITY(' + CAST(ISNULL(ic.seed_value, '0') AS CHAR(1)) + ',' + CAST(ISNULL(ic.increment_value, '1') AS CHAR(1)) + ')' ELSE '' END 
        END + CHAR(13)
    FROM sys.columns c WITH (NOWAIT)
    JOIN sys.types tp WITH (NOWAIT) ON c.user_type_id = tp.user_type_id
    LEFT JOIN sys.computed_columns cc WITH (NOWAIT) ON c.[object_id] = cc.[object_id] AND c.column_id = cc.column_id
    LEFT JOIN sys.default_constraints dc WITH (NOWAIT) ON c.default_object_id != 0 AND c.[object_id] = dc.parent_object_id AND c.column_id = dc.parent_column_id
    LEFT JOIN sys.identity_columns ic WITH (NOWAIT) ON c.is_identity = 1 AND c.[object_id] = ic.[object_id] AND c.column_id = ic.column_id
    WHERE c.[object_id] = @object_id
    ORDER BY c.column_id
    FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, CHAR(9) + ' ')
    + ISNULL((SELECT CHAR(9) + ', CONSTRAINT [' + k.name + '] PRIMARY KEY (' + 
                    (SELECT STUFF((
                         SELECT ', [' + c.name + '] ' + CASE WHEN ic.is_descending_key = 1 THEN 'DESC' ELSE 'ASC' END
                         FROM sys.index_columns ic WITH (NOWAIT)
                         JOIN sys.columns c WITH (NOWAIT) ON c.[object_id] = ic.[object_id] AND c.column_id = ic.column_id
                         WHERE ic.is_included_column = 0
                             AND ic.[object_id] = k.parent_object_id 
                             AND ic.index_id = k.unique_index_id     
                         FOR XML PATH(N''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, ''))
            + ')' + CHAR(13)
            FROM sys.key_constraints k WITH (NOWAIT)
            WHERE k.parent_object_id = @object_id 
                AND k.[type] = 'PK'), '') + ')'  + CHAR(13)
    + ISNULL((SELECT (
        SELECT CHAR(13) +
             'ALTER TABLE ' + @object_name + ' WITH' 
            + CASE WHEN fk.is_not_trusted = 1 
                THEN ' NOCHECK' 
                ELSE ' CHECK' 
              END + 
              ' ADD CONSTRAINT [' + fk.name  + '] FOREIGN KEY(' 
              + STUFF((
                SELECT ', [' + k.cname + ']'
                FROM fk_columns k
                WHERE k.constraint_object_id = fk.[object_id]
                FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '')
               + ')' +
              ' REFERENCES [' + SCHEMA_NAME(ro.[schema_id]) + '].[' + ro.name + '] ('
              + STUFF((
                SELECT ', [' + k.rcname + ']'
                FROM fk_columns k
                WHERE k.constraint_object_id = fk.[object_id]
                FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '')
               + ')'
            + CASE 
                WHEN fk.delete_referential_action = 1 THEN ' ON DELETE CASCADE' 
                WHEN fk.delete_referential_action = 2 THEN ' ON DELETE SET NULL'
                WHEN fk.delete_referential_action = 3 THEN ' ON DELETE SET DEFAULT' 
                ELSE '' 
              END
            + CASE 
                WHEN fk.update_referential_action = 1 THEN ' ON UPDATE CASCADE'
                WHEN fk.update_referential_action = 2 THEN ' ON UPDATE SET NULL'
                WHEN fk.update_referential_action = 3 THEN ' ON UPDATE SET DEFAULT'  
                ELSE '' 
              END 
            + CHAR(13) + 'ALTER TABLE ' + @object_name + ' CHECK CONSTRAINT [' + fk.name  + ']' + CHAR(13)
        FROM sys.foreign_keys fk WITH (NOWAIT)
        JOIN sys.objects ro WITH (NOWAIT) ON ro.[object_id] = fk.referenced_object_id
        WHERE fk.parent_object_id = @object_id
        FOR XML PATH(N''), TYPE).value('.', 'NVARCHAR(MAX)')), '')
    + ISNULL(((SELECT
         CHAR(13) + 'CREATE' + CASE WHEN i.is_unique = 1 THEN ' UNIQUE' ELSE '' END 
                + ' NONCLUSTERED INDEX [' + i.name + '] ON ' + @object_name + ' (' +
                STUFF((

這個查詢比之前的版本更簡潔，并對代碼進(jìn)行了輕微的重構(gòu)，使其更易于閱讀和理解。 它仍然生成完整的 CREATE TABLE 腳本，包括主鍵、外鍵和索引。 請記住將 @table_name 替換為實(shí)際的表名。 例如： SET @table_name = 'MyTable'。 然后執(zhí)行該查詢即可獲得相應(yīng)的 CREATE TABLE 腳本。

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