PHP - 如何选择只有12个字符的列

Question

示例：我希望sql只输出具有6位字符“AAAAAA”的行。我不希望行数超过该值。

Answer 1

"SELECT * FROM table WHERE LENGTH(columnName) = 6" If MySql and
"SELECT * FROM table WHERE LEN(columnName) = 6" If MSSql

Answer 2

SELECT * FROM table WHERE field REGEXP '^[A]{6}$';