handy SQL code snippets

sqlnotes

//concatenante strings, column values
UPDATE table
SET column = CONCAT('text', columnname, 'text')

//lowercase values in one column
UPDATE table SET column = LOWER(column)

//update column value based on value matching to same column or different column
UPDATE table SET column = value WHERE column = value
UPDATE table SET column = value WHERE column IS NULL

//update specific cell value in table 1 with value from a specific cell in table 2. neither cell has matching id or key. 
UPDATE table1 SET column = (
      SELECT column
      FROM table2
      WHERE id = key
  )
WHERE id = key

//update cell value in table 1 with value from table 2 where a specific id/key matches
UPDATE table_1
SET column = table_2.column
FROM table_2 
WHERE table_1.id = table_2.id