在 CTE 中使用子查询，以便我可以使用递归

Question

我需要将多行文本连接成 1 个字符串。我不想使用 FOR XML PATH，因为我需要纯文本，而不是 XML。 我认为使用递归 CTE 可以解决问题，但我需要在 CTE 中使用子查询来创建基本案例，并且 CTE 中的递归案例无法识别子查询表。

这是我的 SQL：

DECLARE @EndCreateTableScript varchar(20) = ') ON [PRIMARY] ';
DECLARE @NewLine varchar(2) = CHAR(13) + CHAR(10);
DECLARE @createTableScript varchar(max)
SET @createTableScript = 'CREATE TABLE [' 


;WITH CTE
AS (
    SELECT ScriptTbl2.RowNumber, ScriptTbl2.CreateTableStart, ScriptTbl2.ColumnScript, ScriptTbl2.EndTableScript
    FROM
        (
            SELECT ROW_NUMBER() OVER (PARTITION BY TableName ORDER BY TableName) AS RowNumber, TableName, 
                    CreateTableStart, ColumnTextStart + DataSizeText + ColumnNullText + @NewLine AS ColumnScript, @EndCreateTableScript + TextImageScript AS EndTableScript
            FROM
            (
                SELECT DISTINCT SchemaName, TableName, @createTableScript + SchemaName + '].[' + TableName + '] ( ' + @NewLine AS CreateTableStart,
                    '[' +ColName + '] [' + DataType + '] ' AS ColumnTextStart,  
                    CASE WHEN DataType in ('bit', 'int', 'money', 'datetime') THEN ' '
                         WHEN DataType in ('numeric', 'decimal') THEN '(' + DataTypePrecision + ', ' + DataTypeScale + ') '
                         WHEN CAST(DataTypeMaxLength AS INT) = -1 THEN '(max) '
                         WHEN DataType in ('varchar', 'varbinary') THEN '('+ DataTypeMaxLength +') '
                         WHEN DataType = 'nvarchar' THEN  '('+ CAST(CAST(DataTypeMaxLength AS INT)/2 AS varchar(5)) +') '
                    END AS DataSizeText,    
                    CASE IsColumnNullable WHEN '0' THEN 'NOT NULL,' ELSE 'NULL,' END AS ColumnNullText,
                    CASE WHEN TextImageFileGroup IS NOT NULL THEN 'TEXTIMAGE_ON [' + TextImageFileGroup + ']' ELSE '' END AS TextImageScript                                                                                                 
                FROM #DBObjectsToAdd
            ) AS ScriptTbl
        ) AS ScriptTbl2
    WHERE RowNumber = 1
    UNION ALL
    SELECT CTE.RowNumber, CTE.CreateTableStart, CTE.ColumnScript + ' ' + ScriptTbl2.ColumnScript, CTE.EndTableScript 
    FROM CTE JOIN #DBObjectsToAdd ScriptTbl ON CTE.RowNumber = ScriptTbl2.RowNumber + 1
    )
    SELECT *
    FROM CTE

问题是子查询表 ScriptTbl2 在递归情况下无法识别。我该如何解决这个问题？

目标是将 ColumnScript 文本连接成每个表格的 1 行文本。

更新 数据并不重要。我只想将多行文本连接成 1 行。 1 表 1 文本 1 2 表 1 文本 2 3 表 1 文本 3 4 表 2 文本 4 5 表2文字5

使用 CTE 递归或其他一些类型的查询更改为： 1 表 1 文本 1 文本 2 文本 3 2 表2 文本4 文本5

更新 我创建了一个临时表，需要 Row_Number 进行递归和 3 个文本字段。

CREATE TABLE #TableScripts(RowNumber int, TableStart varchar(100), ColumnScript varchar(max), TableEnd varchar(100))

这是添加数据的SELECT 查询。

SELECT RowNumber, TableName, CreateTableStart, ColumnScript, TextImageScript
FROM
(
    SELECT DISTINCT ROW_NUMBER() OVER (PARTITION BY TableName ORDER BY TableName) AS RowNumber,
                SchemaName, TableName, @createTableScript + SchemaName + '].[' + TableName + '] ( ' + @NewLine AS CreateTableStart,
        ('[' +ColName + '] [' + DataType + '] ') +  
        (CASE WHEN DataType in ('bit', 'int', 'money', 'datetime') THEN ' '
                WHEN DataType in ('numeric', 'decimal') THEN '(' + DataTypePrecision + ', ' + DataTypeScale + ') '
                WHEN CAST(DataTypeMaxLength AS INT) = -1 THEN '(max) '
                WHEN DataType in ('varchar', 'varbinary') THEN '('+ DataTypeMaxLength +') '
                WHEN DataType = 'nvarchar' THEN  '('+ CAST(CAST(DataTypeMaxLength AS INT)/2 AS varchar(5)) +') '
        END) +  
        (CASE IsColumnNullable WHEN '0' THEN 'NOT NULL,' ELSE 'NULL,' END) + @NewLine AS ColumnScript,
            @EndCreateTableScript + (CASE WHEN TextImageFileGroup IS NOT NULL THEN 'TEXTIMAGE_ON [' + TextImageFileGroup + ']' ELSE '' END)  AS TextImageScript                                                                                                  
    FROM #DBObjectsToAdd
) AS ScriptTbl      
ORDER BY TableName

出于某种原因，将ROW_NUMBER 函数添加到查询中会将其中1 个表的行数从2（它只有2 列）增加到32。

Answer 1

我认为这只是递归部分中对 JOIN 的错误引用，但这并不是问题所在。

您正在引用 CTE，可以将其视为递归的上一次迭代。但是对于您的“当前迭代”，您尝试引用 ScriptTbl2，但 ScriptTbl2 仅存在于“锚”查询中 - 您必须使用 ROW_NUMBER() 等重做该查询，以在递归部分构建您自己的 ScriptTbl2 .

可能是这样的：

DECLARE @EndCreateTableScript varchar(20) = ') ON [PRIMARY] ';
DECLARE @NewLine varchar(2) = CHAR(13) + CHAR(10);
DECLARE @createTableScript varchar(max)
SET @createTableScript = 'CREATE TABLE [' 


;WITH CTE
AS (
    SELECT ScriptTbl2.RowNumber, ScriptTbl2.CreateTableStart, ScriptTbl2.ColumnScript, ScriptTbl2.EndTableScript
    FROM
        (
            SELECT ROW_NUMBER() OVER (PARTITION BY TableName ORDER BY TableName) AS RowNumber, TableName, 
                    CreateTableStart, ColumnTextStart + DataSizeText + ColumnNullText + @NewLine AS ColumnScript, @EndCreateTableScript + TextImageScript AS EndTableScript
            FROM
            (
                SELECT DISTINCT SchemaName, TableName, @createTableScript + SchemaName + '].[' + TableName + '] ( ' + @NewLine AS CreateTableStart,
                    '[' +ColName + '] [' + DataType + '] ' AS ColumnTextStart,  
                    CASE WHEN DataType in ('bit', 'int', 'money', 'datetime') THEN ' '
                         WHEN DataType in ('numeric', 'decimal') THEN '(' + DataTypePrecision + ', ' + DataTypeScale + ') '
                         WHEN CAST(DataTypeMaxLength AS INT) = -1 THEN '(max) '
                         WHEN DataType in ('varchar', 'varbinary') THEN '('+ DataTypeMaxLength +') '
                         WHEN DataType = 'nvarchar' THEN  '('+ CAST(CAST(DataTypeMaxLength AS INT)/2 AS varchar(5)) +') '
                    END AS DataSizeText,    
                    CASE IsColumnNullable WHEN '0' THEN 'NOT NULL,' ELSE 'NULL,' END AS ColumnNullText,
                    CASE WHEN TextImageFileGroup IS NOT NULL THEN 'TEXTIMAGE_ON [' + TextImageFileGroup + ']' ELSE '' END AS TextImageScript                                                                                                 
                FROM #DBObjectsToAdd
            ) AS ScriptTbl
        ) AS ScriptTbl2
    WHERE RowNumber = 1
    UNION ALL
    SELECT CTE.RowNumber, CTE.CreateTableStart, CTE.ColumnScript + ' ' + ScriptTbl2.ColumnScript, CTE.EndTableScript 
    FROM CTE JOIN (
        SELECT ScriptTbl2.RowNumber, ScriptTbl2.CreateTableStart, ScriptTbl2.ColumnScript, ScriptTbl2.EndTableScript
        FROM (
            SELECT ROW_NUMBER() OVER (PARTITION BY TableName ORDER BY TableName) AS RowNumber, TableName, 
                    CreateTableStart, ColumnTextStart + DataSizeText + ColumnNullText + @NewLine AS ColumnScript, @EndCreateTableScript + TextImageScript AS EndTableScript
            FROM
            (
                SELECT DISTINCT SchemaName, TableName, @createTableScript + SchemaName + '].[' + TableName + '] ( ' + @NewLine AS CreateTableStart,
                    '[' +ColName + '] [' + DataType + '] ' AS ColumnTextStart,  
                    CASE WHEN DataType in ('bit', 'int', 'money', 'datetime') THEN ' '
                         WHEN DataType in ('numeric', 'decimal') THEN '(' + DataTypePrecision + ', ' + DataTypeScale + ') '
                         WHEN CAST(DataTypeMaxLength AS INT) = -1 THEN '(max) '
                         WHEN DataType in ('varchar', 'varbinary') THEN '('+ DataTypeMaxLength +') '
                         WHEN DataType = 'nvarchar' THEN  '('+ CAST(CAST(DataTypeMaxLength AS INT)/2 AS varchar(5)) +') '
                    END AS DataSizeText,    
                    CASE IsColumnNullable WHEN '0' THEN 'NOT NULL,' ELSE 'NULL,' END AS ColumnNullText,
                    CASE WHEN TextImageFileGroup IS NOT NULL THEN 'TEXTIMAGE_ON [' + TextImageFileGroup + ']' ELSE '' END AS TextImageScript                                                                                                 
                FROM #DBObjectsToAdd
            ) AS ScriptTbl
        ) AS ScriptTbl2
    ) AS ScriptTbl3
    ON ScriptTbl3.RowNumber = CTE.RowNumber + 1 --you want each iteration to increase, right?
)
SELECT *
FROM CTE