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# Transact-SQL

## begin transaction

``` sql
begin transaction
-- ...insert or whatever...
commit; -- if all ok
rollback; --if not ok
```

## check memory of DB server

```
SELECT
  (physical_memory_in_use_kb/1024) AS Memory_usedby_Sqlserver_MB,
  (locked_page_allocations_kb/1024) AS Locked_pages_used_Sqlserver_MB,
  (total_virtual_address_space_kb/1024) AS Total_VAS_in_MB,
  process_physical_memory_low,
  process_virtual_memory_low
FROM sys.dm_os_process_memory;
```

## Check if a List of numbers exist in a table:

``` sql
-- declare array
DECLARE @IDList TABLE (ID INT);

-- fill array
INSERT INTO @IDList (ID)
VALUES (274), (7238), (7546), (7719), (36227);

-- create table with id and exists/not exist
SELECT l.ID, CASE WHEN vv.OBJ_ID IS NOT NULL THEN 'Exists' ELSE 'Does Not Exist' END AS Status
FROM @IDList l
LEFT JOIN VAL vv ON l.ID = vv.OBJ_ID;
```

## String Suche über alle Tables einer DB

``` sql
DECLARE @SearchStr NVARCHAR(100) = '%wikidata%' -- Replace with the string you want to search
DECLARE @SQL NVARCHAR(MAX) = ''

-- Generate the SQL for each table and column
SELECT @SQL = @SQL + 'SELECT ''' + TABLE_SCHEMA + '.' + TABLE_NAME + ''' AS TableName, ''' 
    + COLUMN_NAME + ''' AS ColumnName, ' 
    + 'CAST(' + QUOTENAME(COLUMN_NAME) + ' AS NVARCHAR(4000)) AS ColumnValue ' 
    + 'FROM ' + QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME) + ' ' 
    + 'WHERE CAST(' + QUOTENAME(COLUMN_NAME) + ' AS NVARCHAR(4000)) LIKE ''%' + @SearchStr + '%'' UNION ALL '
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE DATA_TYPE IN ('char', 'varchar', 'nchar', 'nvarchar', 'text', 'ntext')

-- Remove the last UNION ALL
SET @SQL = LEFT(@SQL, LEN(@SQL) - 10)

-- Execute the dynamically constructed SQL
EXEC sp_executesql @SQL
```

## convert Unix Timestamp to date

``` sql
SELECT pid, 
  dateadd(hh,-5,dateadd(s, convert(bigint, cDate) / 1000, convert(datetime,'1-1-1970 00:00:00'))), 
  dateadd(hh,-5,dateadd(s, convert(bigint, mDate) / 1000, convert(datetime,'1-1-1970 00:00:00'))), 
  mDate,
  dcTitle 
  FROM databasename_xy.dbo.tablename_xy
  WHERE pid like 'test:%'';
```

## Mehrere Zeilen zusammen in 1 Zeile mergen

Annahme:
  - Tabelle hat Spalten OBJ_ID, VAL_TEXT, FLD_ID
  - OBJ_ID hat mehrere Einträge, mit unterschiedlichen Werten in VAL_TEXT und FLD_ID. Halt je nach Feld andere Feldwerte.
  - Ich möchte eine Query, die mir 1 Zeile pro OBJ_ID ausgibt, mit 1 Spalte "url" und 1 Spalte "Name"
  - "url" ist in VAL_TEXT mit FLD_ID xy (in diesem Bsp. egal) enthalten
  - "name" ist in VAL_TEXT mit FLD_ID 40414 enthalten
  - Bei der Query soll nur die OBJ_ID berücksichtig werden, die in einem VAL_TEXT "%wikidata%" drin hat

``` sql
WITH CTE_Wikidata AS (
    -- Sammle alle OBJ_IDs, bei denen VAL_TEXT "wikidata" enthält
    SELECT OBJ_ID, VAL_TEXT AS url
    FROM VAL
    WHERE VAL_TEXT LIKE '%wikidata%'
),
CTE_Person AS (
    -- Sammle alle OBJ_IDs, bei denen FLD_ID = 240414 und die in CTE_Wikidata existieren
    SELECT v.OBJ_ID, v.VAL_TEXT AS person
    FROM VAL v
    INNER JOIN CTE_Wikidata wd ON v.OBJ_ID = wd.OBJ_ID
    WHERE v.FLD_ID = 40414
)
SELECT 
    wd.OBJ_ID,
    wd.url,
    p.person
FROM CTE_Wikidata wd
LEFT JOIN CTE_Person p ON wd.OBJ_ID = p.OBJ_ID;
```