Wie kann ich CREATE-Tabellenskripte für vorhandene Tabellen in SQL Server generieren?

Skript mit Abfrage erstellen, um eine vorhandene Tabelle zu generieren

Viele Benutzer suchen nach einer Möglichkeit, CREATE-Skripte für vorhandene Tabellen in SQL Server zu generieren, insbesondere wenn diese Tabellen keine Daten enthalten. Dazu ist es wichtig, die Mechanismen der Abfrage von Systemtabellen wie sys.tables zu verstehen.

Abfrage, die zum Generieren des CREATE Table-Skripts verwendet wird

Die folgende Abfrage zeigt, wie ein CREATE-Skript für jede vorhandene Tabelle in der Datenbank generiert wird:

<code class="language-sql">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((</code>

Diese Abfrage ist prägnanter als die vorherige Version und der Code wurde leicht überarbeitet, um ihn leichter lesbar und verständlich zu machen. Es generiert weiterhin das vollständige CREATE TABLE-Skript, einschließlich Primärschlüssel, Fremdschlüssel und Indizes. Denken Sie daran, @table_name durch den tatsächlichen Tabellennamen zu ersetzen. Zum Beispiel: SET @table_name = 'MyTable'. Führen Sie dann die Abfrage aus, um das entsprechende CREATE TABLE-Skript zu erhalten.

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