sp_BlitzLock: Fix bugs and code quality issues from full code review

Bug fixes:
- AND/OR precedence in Check 2: Added parentheses around OR conditions in
  the shared-lock deadlock check. Without them, all filter parameters
  (@DatabaseName, @StartDate, @EndDate, @objectname) were ignored because
  the OR chain short-circuited the AND conditions.
- SQL injection: Added QUOTENAME() around @OutputDatabaseName and
  @OutputSchemaName in the first dynamic SQL block (pre-"protection spells").
  The later blocks were already protected.
- Azure event_file: Changed sys.dm_xe_database_session_targets (DMV with
  varbinary/sysname columns) to sys.database_event_session_targets (catalog
  view with int columns) to match the JOIN column types. Same fix for the
  fields DMV. Validated against Microsoft Learn documentation.
- NULL bypass in session validation: When @TargetSessionType is NULL (the
  default), the <> N'table' comparison evaluated to UNKNOWN, skipping XE
  session existence checks entirely. Added IS NULL OR guard on both Azure
  and non-Azure paths.
- check_id mismatch: Check 16 (implicit transaction deadlocks) was
  inserting with check_id = 14 instead of 16.
- Multi-victim deadlocks: Replaced computed column that compared
  victim_id via .value() (only catches first victim) with a regular
  column + UPDATE using .exist() with sql:column() to correctly identify
  all victims in multi-victim deadlock scenarios. Tested with fabricated
  3-way deadlock XML.
- Memory grant 8x overstatement: Removed erroneous * 8. multiplier from
  min/max_grant_kb and min/max_used_grant_kb conversions to MB. These
  columns from sys.dm_exec_query_stats are already in KB, not pages.
- @StartDate > @EndDate: Added validation with RAISERROR when the caller
  passes a start date after the end date.
- LOWER() consistency: All @TargetSessionType LIKE comparisons now use
  LOWER() for case-insensitive matching. Previously only the N'table'
  comparisons used LOWER(), while ring_buffer and event_file did not.
  Validated with uppercase parameter values on SQL2022.

Code quality:
- Removed unused variables @DeadlockCount and @ServerName (and their
  debug output references).
- Changed @OutputDatabaseCheck default from -1 to 1 (bit type).
- Changed @ProductVersionMajor from float to decimal(5,1) to avoid
  floating-point representation issues with version numbers.
- Fixed 4 copy-paste comments that all said "Add wait_resource column"
  but were for client_option_1, client_option_2, lock_mode, and status.
- Added dbo schema filter to synonym existence checks for DeadlockFindings
  and DeadLockTbl to avoid matching synonyms in other schemas.
- Changed RTRIM(COUNT_BIG(...)) to CONVERT(nvarchar(20), COUNT_BIG(...))
  in Check 13 for explicit type conversion instead of relying on implicit
  cast through RTRIM.

Tested: 22 execution scenarios on SQL2022 including default, all filter
parameters, VictimsOnly, ExportToExcel, Debug, Help, output to table,
ring_buffer/event_file/table targets, uppercase target types, bogus
session names, nonexistent databases, date validation, and narrow date
ranges. All passed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: erikdarlingdata

sp_BlitzLock.sql

@@ -151,7 +151,7 @@ BEGIN
             DB_ID(@DatabaseName),
         @ProductVersion nvarchar(128) =
             CAST(SERVERPROPERTY('ProductVersion') AS nvarchar(128)),
-        @ProductVersionMajor float =
+        @ProductVersionMajor decimal(5,1) =
             SUBSTRING
             (
                 CAST(SERVERPROPERTY('ProductVersion') AS nvarchar(128)),
@@ -210,9 +210,7 @@ BEGIN
         @StringToExecuteParams nvarchar(500) = N'',
         @r sysname = NULL,
         @OutputTableFindings nvarchar(100) = N'[BlitzLockFindings]',
-        @DeadlockCount int = 0,
-        @ServerName sysname = @@SERVERNAME,
-        @OutputDatabaseCheck bit = -1,
+        @OutputDatabaseCheck bit = 1,
         @SessionId int = 0,
         @TargetSessionId int = 0,
         @FileName nvarchar(4000) = N'',
@@ -339,6 +337,12 @@ BEGIN
         @StartDateUTC = @StartDate,
         @EndDateUTC = @EndDate;
 
+    IF @StartDate > @EndDate
+    BEGIN
+        RAISERROR('@StartDate cannot be after @EndDate.', 11, 1) WITH NOWAIT;
+        RETURN;
+    END;
+
     IF
     (
             @MI = 1
@@ -528,7 +532,7 @@ BEGIN
 
 
     IF @Azure = 0
-    AND LOWER(@TargetSessionType) <> N'table'
+    AND (@TargetSessionType IS NULL OR LOWER(@TargetSessionType) <> N'table')
     BEGIN
         IF NOT EXISTS
         (
@@ -547,7 +551,7 @@ BEGIN
     END;
 
     IF @Azure = 1
-    AND LOWER(@TargetSessionType) <> N'table'
+    AND (@TargetSessionType IS NULL OR LOWER(@TargetSessionType) <> N'table')
     BEGIN
         IF NOT EXISTS
         (
@@ -588,18 +592,22 @@ BEGIN
             SELECT
                 @StringToExecute =
                     N'SELECT @r = o.name FROM ' +
-                    @OutputDatabaseName +
+                    QUOTENAME(@OutputDatabaseName) +
                     N'.sys.objects AS o inner join ' +
-                    @OutputDatabaseName +
+                    QUOTENAME(@OutputDatabaseName) +
                     N'.sys.schemas as s on o.schema_id = s.schema_id WHERE o.type_desc = N''USER_TABLE'' AND o.name = ' +
                     QUOTENAME
                     (
                         @OutputTableName,
                         N''''
                     ) +
-                    N' AND s.name =''' +
-                    @OutputSchemaName +
-                    N''';',
+                    N' AND s.name = ' +
+                    QUOTENAME
+                    (
+                        @OutputSchemaName,
+                        N''''
+                    ) +
+                    N';',
                 @StringToExecuteParams =
                     N'@r sysname OUTPUT';
 
@@ -670,7 +678,7 @@ BEGIN
                         N'.sys.all_columns AS o WHERE o.object_id = (OBJECT_ID(''' +
                         @ObjectFullName +
                         N''')) AND o.name = N''client_option_1'')
-                        /*Add wait_resource column*/
+                        /*Add client_option_1 column*/
                         ALTER TABLE ' +
                         @ObjectFullName +
                         N' ADD client_option_1 varchar(500) NULL;';
@@ -686,7 +694,7 @@ BEGIN
                         N'.sys.all_columns AS o WHERE o.object_id = (OBJECT_ID(''' +
                         @ObjectFullName +
                         N''')) AND o.name = N''client_option_2'')
-                        /*Add wait_resource column*/
+                        /*Add client_option_2 column*/
                         ALTER TABLE ' +
                         @ObjectFullName +
                         N' ADD client_option_2 varchar(500) NULL;';
@@ -702,7 +710,7 @@ BEGIN
                         N'.sys.all_columns AS o WHERE o.object_id = (OBJECT_ID(''' +
                         @ObjectFullName +
                         N''')) AND o.name = N''lock_mode'')
-                        /*Add wait_resource column*/
+                        /*Add lock_mode column*/
                         ALTER TABLE ' +
                         @ObjectFullName +
                         N' ADD lock_mode nvarchar(256) NULL;';
@@ -718,7 +726,7 @@ BEGIN
                         N'.sys.all_columns AS o WHERE o.object_id = (OBJECT_ID(''' +
                         @ObjectFullName +
                         N''')) AND o.name = N''status'')
-                        /*Add wait_resource column*/
+                        /*Add status column*/
                         ALTER TABLE ' +
                         @ObjectFullName +
                         N' ADD status nvarchar(256) NULL;';
@@ -851,7 +859,10 @@ BEGIN
                 SELECT
                     1/0
                 FROM sys.objects AS o
+                JOIN sys.schemas AS s
+                  ON o.schema_id = s.schema_id
                 WHERE o.name = N'DeadlockFindings'
+                AND   s.name = N'dbo'
                 AND   o.type_desc = N'SYNONYM'
             )
             BEGIN
@@ -878,7 +889,10 @@ BEGIN
                 SELECT
                     1/0
                 FROM sys.objects AS o
+                JOIN sys.schemas AS s
+                  ON o.schema_id = s.schema_id
                 WHERE o.name = N'DeadLockTbl'
+                AND   s.name = N'dbo'
                 AND   o.type_desc = N'SYNONYM'
             )
             BEGIN
@@ -993,7 +1007,7 @@ BEGIN
     /*If ring buffers*/
     IF
     (
-           @TargetSessionType LIKE N'ring%'
+           LOWER(@TargetSessionType) LIKE N'ring%'
        AND @EventSessionName NOT LIKE N'system_health%'
     )
     BEGIN
@@ -1048,7 +1062,7 @@ BEGIN
     /*If event file*/
     IF
     (
-           @TargetSessionType LIKE N'event%'
+           LOWER(@TargetSessionType) LIKE N'event%'
        AND @EventSessionName NOT LIKE N'system_health%'
     )
     BEGIN
@@ -1093,13 +1107,13 @@ BEGIN
             RAISERROR('@TargetSessionType is event_file, assigning XML for Azure', 0, 1) WITH NOWAIT;
             SELECT
                 @SessionId =
-                    t.event_session_address,
+                    t.event_session_id,
                 @TargetSessionId =
-                    t.target_name
-            FROM sys.dm_xe_database_session_targets t
-            JOIN sys.dm_xe_database_sessions s
-              ON s.address = t.event_session_address
-            WHERE t.target_name = @TargetSessionType
+                    t.target_id
+            FROM sys.database_event_session_targets AS t
+            JOIN sys.database_event_sessions AS s
+              ON s.event_session_id = t.event_session_id
+            WHERE t.name = @TargetSessionType
             AND   s.name = @EventSessionName
             OPTION(RECOMPILE);
 
@@ -1117,7 +1131,7 @@ BEGIN
                 SELECT
                     file_name =
                         CONVERT(nvarchar(4000), f.value)
-                FROM sys.server_event_session_fields AS f
+                FROM sys.database_event_session_fields AS f
                 WHERE f.event_session_id = @SessionId
                 AND   f.object_id = @TargetSessionId
                 AND   f.name = N'filename'
@@ -1149,7 +1163,7 @@ BEGIN
     /*If ring buffers*/
     IF
     (
-           @TargetSessionType LIKE N'ring%'
+           LOWER(@TargetSessionType) LIKE N'ring%'
        AND @EventSessionName NOT LIKE N'system_health%'
     )
     BEGIN
@@ -1184,7 +1198,7 @@ BEGIN
     /*If event file*/
     IF
     (
-           @TargetSessionType LIKE N'event_file%'
+           LOWER(@TargetSessionType) LIKE N'event_file%'
        AND @EventSessionName NOT LIKE N'system_health%'
     )
     BEGIN
@@ -1223,7 +1237,7 @@ BEGIN
     /*This section deals with event file*/
     IF
     (
-           @TargetSessionType LIKE N'event%'
+           LOWER(@TargetSessionType) LIKE N'event%'
        AND @EventSessionName LIKE N'system_health%'
     )
     BEGIN
@@ -2005,16 +2019,15 @@ BEGIN
         ADD
             waiter_mode nvarchar(256),
             owner_mode nvarchar(256),
-            is_victim AS
-                CONVERT
-                (
-                    bit,
-                    CASE
-                        WHEN id = victim_id
-                        THEN 1
-                        ELSE 0
-                    END
-                ) PERSISTED;
+            is_victim bit NOT NULL DEFAULT 0;
+
+        UPDATE
+            dp
+        SET
+            dp.is_victim = 1
+        FROM #deadlock_process AS dp
+        WHERE dp.deadlock_graph.exist('deadlock/victim-list/victimProcess[@id = sql:column("dp.id")]') = 1
+        OPTION(RECOMPILE);
 
         /*Update some nonsense*/
         SET @d = CONVERT(varchar(40), GETDATE(), 109);
@@ -2346,21 +2359,24 @@ BEGIN
                 OVER (ORDER BY COUNT_BIG(DISTINCT dow.event_date) DESC)
         FROM #deadlock_owner_waiter AS dow
         WHERE 1 = 1
-        AND dow.lock_mode IN
-            (
-                N'S',
-                N'IS'
-            )
-        OR  dow.owner_mode IN
-            (
-                N'S',
-                N'IS'
-            )
-        OR  dow.waiter_mode IN
-            (
-                N'S',
-                N'IS'
-            )
+        AND
+        (
+            dow.lock_mode IN
+                (
+                    N'S',
+                    N'IS'
+                )
+            OR  dow.owner_mode IN
+                (
+                    N'S',
+                    N'IS'
+                )
+            OR  dow.waiter_mode IN
+                (
+                    N'S',
+                    N'IS'
+                )
+        )
         AND (dow.database_id = @DatabaseId OR @DatabaseName IS NULL)
         AND (dow.event_date >= @StartDate OR @StartDate IS NULL)
         AND (dow.event_date < @EndDate OR @EndDate IS NULL)
@@ -3360,7 +3376,7 @@ BEGIN
             finding_group = N'Agent Job Deadlocks',
             finding =
                 N'There have been ' +
-                RTRIM(COUNT_BIG(DISTINCT aj.event_date)) +
+                CONVERT(nvarchar(20), COUNT_BIG(DISTINCT aj.event_date)) +
                 N' deadlocks from this Agent Job and Step.',
             sort_order = 
                 ROW_NUMBER()
@@ -3480,7 +3496,7 @@ BEGIN
             finding
         )
         SELECT
-            check_id = 14,
+            check_id = 16,
             database_name = N'-',
             object_name = N'-',
             finding_group = N'Total implicit transaction deadlocks',
@@ -4224,13 +4240,13 @@ BEGIN
                     total_logical_reads_mb =
                         deqs.total_logical_reads * 8. / 1024.,
                     min_grant_mb =
-                        deqs.min_grant_kb * 8. / 1024.,
+                        deqs.min_grant_kb / 1024.,
                     max_grant_mb =
-                        deqs.max_grant_kb * 8. / 1024.,
+                        deqs.max_grant_kb / 1024.,
                     min_used_grant_mb =
-                        deqs.min_used_grant_kb * 8. / 1024.,
+                        deqs.min_used_grant_kb / 1024.,
                     max_used_grant_mb =
-                        deqs.max_used_grant_kb * 8. / 1024.,  
+                        deqs.max_used_grant_kb / 1024.,  
                     deqs.min_reserved_threads,
                     deqs.max_reserved_threads,
                     deqs.min_used_threads,
@@ -4538,10 +4554,6 @@ BEGIN
                 @r,
             OutputTableFindings =
                 @OutputTableFindings,
-            DeadlockCount =
-                @DeadlockCount,
-            ServerName =
-                @ServerName,
             OutputDatabaseCheck =
                 @OutputDatabaseCheck,
             SessionId =