GROUP_CONCAT MYSQL group by function
GROUP_CONCAT() function is used to concatenate column values into a single string. Note that this function will not count null values. This is very useful group by function if you need records from database with multiple rows in single string with specified separator(e.g. Comma separated). This situation will come in one to may relation of tables. You may get this error while retrieving records using joins. “Operand should contain 1 column(s)”.
Table tbl_users have 4 records in column “name”.
SELECT name FROM tbl_users;
SELECT GROUP_CONCAT(name) FROM tbl_users;
Let me know if you find any problem.