multiple values in mysql variable

There's good solution described here: https://stackoverflow.com/a/11957706/1523961

So you can use something like this:

SET @a := '20100630,20100701';
SELECT * FROM wordbase WHERE FIND_IN_SET(verified, @a);

Also, if you're selecting the ids for @a from another table, you can come up with the following:

SET @a := (SELECT GROUP_CONCAT(id) FROM someTable where yourBooleanExpressionHere);
SELECT * FROM wordbase WHERE FIND_IN_SET(verified, @a);

You cannot (as far as I am aware) store multiple values in a MySQL user defined variable. What you have done is create a string which contains:

'20100630', '20100701'

That is not two separate values, but a single string value, just as this is a single string value:

SET @a := "It's a single string, and that's the problem";

You need to use two separate variables, or prepare a statement, like this:

SET @a := "20100630";
SET @b := "20100701";

SET @sql = CONCAT(
    'SELECT * FROM wordbase WHERE verified IN (',
    @a,
    ',',
    @b,
    ')'
);


SELECT @sql;
+--------------------------------------------------------------+
| @sql                                                         |
+--------------------------------------------------------------+
| SELECT * FROM wordbase WHERE verified IN (20100630,20100701) |
+--------------------------------------------------------------+

PREPARE stmt FROM @sql;
EXECUTE stmt;

But that's kinda messy. Why do you need to use variables?

Using GROUP_CONCAT and GROUP BY one could pull all values ( i.e. an id ) into a variable like so:

SET @var := (SELECT GROUP_CONCAT(id) FROM `table` WHERE `verified` = @verified GROUP BY verified);