Cascading Delete And Finding Table Reference Level

This function will generate all DELETE statements in correct order to perform a CASCADING delete.
For self-joined tables, it will generate the T-SQL code to "unwind" the table, also in correct order!CREATE FUNCTION dbo.fnCascadingDelete
(
@Schema NVARCHAR(128) = NULL,
@Table NVARCHAR(128) = NULL
)
RETURNS@Return TABLE
(
RowID INT PRIMARY KEY CLUSTERED,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL,
[SQL] NVARCHAR(4000) NOT NULL
)
AS
BEGIN
DECLARE@Constraints TABLE
(
RowID INT NOT NULL,
Indent SMALLINT NOT NULL,
[Catalog] NVARCHAR(128) NOT NULL,
[Schema] NVARCHAR(128) NOT NULL,
[Table] NVARCHAR(128) NOT NULL,
[Column] NVARCHAR(128),
pkCatalog NVARCHAR(128),
pkSchema NVARCHAR(128),
pkTable NVARCHAR(128),
pkColumn NVARCHAR(128),
pkType NVARCHAR(128),
pkSize INT,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL
)

INSERT@Constraints
(
RowID,
Indent,
[Catalog],
[Schema],
[Table],
[Column],
pkCatalog,
pkSchema,
pkTable,
pkColumn,
pkType,
pkSize,
IsSelfJoin,
HasPk
)
SELECTRowID,
Indent,
[Catalog],
[Schema],
[Table],
[Column],
pkCatalog,
pkSchema,
pkTable,
pkColumn,
pkType,
pkSize,
SelfJoin,
CASE
WHEN [Column] IS NULL THEN 0
ELSE 1
END
FROMdbo.fnTableTree(@Schema, @Table)

IF @@ROWCOUNT = 0
RETURN

DECLARE@SQL TABLE
(
ID INT IDENTITY(1, 1),
RowID INT PRIMARY KEY CLUSTERED,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL,
[SQL] NVARCHAR(4000) NOT NULL
)

DECLARE@Indent SMALLINT,
@RowID INT,
@ID INT,
@TSQL NVARCHAR(4000),
@RowSQL NVARCHAR(4000),
@EndSQL NVARCHAR(4000),
@pkColumn NVARCHAR(128),
@IsSelfJoin TINYINT,
@HasPk TINYINT

DECLARE@Unwind TABLE
(
RowID INT NOT NULL,
StepID INT IDENTITY(0, 1) PRIMARY KEY NONCLUSTERED,
[SQL] NVARCHAR(4000)
)

WHILE NOT EXISTS (SELECT * FROM @SQL WHERE RowID = 1)
BEGIN
SELECT TOP 1@RowID = c.RowID,
@ID = c.RowID,
@Indent = c.Indent,
@TSQL = N'',
@EndSQL = N'',
@IsSelfJoin = c.IsSelfjoin,
@HasPk = c.HasPk
FROM@Constraints AS c
LEFT JOIN@SQL AS s ON s.RowID = c.RowID
WHEREs.RowID IS NULL
ORDER BYc.Indent DESC,
c.RowID DESC

WHILE @ID > 0
BEGIN
IF @Indent = 0
SELECT@RowSQL = N'DELETE t' + CAST(@RowID AS NVARCHAR(12)),
@RowSQL = @RowSQL + N' FROM ' + QUOTENAME(c.[Catalog]) + N'.' + QUOTENAME(c.[Schema]) + N'.' + QUOTENAME(c.[Table]) + N' AS t' + CAST(@ID AS NVARCHAR(12)),
@EndSQL = N' WHERE t' + CAST(@ID AS NVARCHAR(12)) + '.' + QUOTENAME(COALESCE(c.[Column], '%0')) + N' = ''%1''',
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID = @ID
ELSE
SELECT@RowSQL = N' INNER JOIN ' + QUOTENAME(c.[Catalog]) + N'.' + QUOTENAME(c.[Schema]) + N'.' + QUOTENAME(c.[Table]),
@RowSQL = @RowSQL + N' AS t' + CAST(@ID AS NVARCHAR(12)) + N' ON t' + CAST(@ID AS NVARCHAR(12)) + N'.' + QUOTENAME(c.[Column]),
@pkColumn = QUOTENAME(c.pkColumn),
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID = @ID

SELECT TOP 1@ID = c.RowID,
@Indent = c.Indent,
@RowSQL = @RowSQL + N' = t' + CAST(c.RowID AS NVARCHAR(12)) + N'.' + @pkColumn,
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID < @ID
AND c.Indent < @Indent
ORDER BYc.Indent DESC,
c.RowID DESC

IF @@ROWCOUNT = 0
SET@ID = 0

SET@TSQL = @RowSQL + @TSQL
END

INSERT@SQL
(
RowID,
IsSelfJoin,
HasPk,
[SQL]
)
VALUES(
@RowID,
@IsSelfJoin,
@HasPk,
@TSQL + @EndSQL
)

IF @IsSelfJoin = 1
BEGIN
DECLARE@Yak NVARCHAR(160),
@Catalog NVARCHAR(128),
@Column NVARCHAR(128)

SELECT@Yak = pkType + COALESCE('(' + CAST(pkSize AS NVARCHAR(12)) + ')', ''),
@Catalog = [Catalog],
@Schema = [Schema],
@Table = [Table],
@Column = [Column],
@Catalog = [Catalog],
@Table = [Table],
@pkColumn = pkColumn
FROM@Constraints
WHERERowID = @RowID

SET@RowSQL = 'DECLARE@Lvl INT
SET@Lvl = 0
DECLARE@Stage TABLE (RowID INT IDENTITY(0, 1), Lvl INT, RowKey ' + @Yak + ')
INSERT @Stage (Lvl, RowKey) '
+ REPLACE(@TSQL + @EndSQL, 'DELETE t' + CAST(@RowID AS NVARCHAR(12)) + '', 'SELECT 0, t' + CAST(@RowID AS NVARCHAR(12)) + '.' + QUOTENAME(@Column) + '')
+ ' WHILE @@ROWCOUNT > 0
BEGIN
SET@Lvl = @Lvl + 1

INSERT@Stage (Lvl, RowKey)
SELECT@Lvl,
t.' + QUOTENAME(@pkColumn) + '
FROM' + QUOTENAME(@Catalog) + '.' + QUOTENAME(@Schema) + '.' + QUOTENAME(@Table) + ' AS t
INNER JOIN@Stage AS s ON s.RowKey = t.' + QUOTENAME(@Column) + '
AND s.Lvl = @Lvl - 1
LEFT JOIN@Stage AS cr ON cr.RowKey = t.' + QUOTENAME(@pkColumn) + '
WHEREcr.RowKey IS NULL
END
SELECT ''DELETE FROM ' + QUOTENAME(@Catalog) + '.' + QUOTENAME(@Schema) + '.' + QUOTENAME(@Table) + ' WHERE ' + QUOTENAME(@pkColumn) + ' = '' + QUOTENAME(RowKey, '''''''')
FROM @Stage
WHERE RowID > 0
ORDER BY RowID DESC'

INSERT@Unwind
(
RowID,
[SQL]
)
VALUES(
@RowID,
@RowSQL
)
END
END

INSERT@Return
(
RowID,
IsSelfJoin,
HasPk,
[SQL]
)
SELECTs.ID,
s.IsSelfJoin,
s.HasPk,
CASE
WHEN u.RowID IS NULL THEN s.[SQL]
ELSE u.[SQL]
END
FROM@SQL AS s
LEFT JOIN@Unwind AS u ON u.RowID = s.RowID
ORDER BYs.ID,
u.StepID

RETURN
ENDE 12°55'05.25"
N 56°04'39.16"