如何在mysql的同一列上使用LEFT和REPLACE？

Question

I want to select a column and remove(replace with space) any line feeds or carriage returns and I want to get only the first 40 characters in the column after the replace.

Here is the query I tried but I get

select date, REPLACE(LEFT(message, '\r', ' '), 30)
from table1 
where message like 'testing%'

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ' ' '), 30) from events_cleared where message like 'testing%' ' at line 1

Answer 1

Replace needs the arguments '\\r; and ' '

LEFT(REPLACE(message, '\r', ' '), 30)

or

REPLACE(LEFT(message,30), '\r', ' ')

Answer 2

You have the ordering of your arguments incorrect (you have passed the REPLACE arguments to LEFT ). Try this:

select date, REPLACE(LEFT(message, 30), '\r', ' ')
from table1 
where message like 'testing%'

Answer 3

Your function identifiers are switched and therefore the number of arguments weren't right. if you want replace() to happen first is has to go deeper in the nesting than the left() . You also wrote 30 as second argument to left() which would give you only 30 characters, not 40.

SELECT date,
       left(replace(message, '\r', ' '), 40)
       FROM table1
       WHERE message LIKE 'testing%';