为什么查询字符串处理regexp无法正常工作

Question

SELECT col_x, col_y FROM table_name WHERE col_z = 'yello'  LIMIT k;
col_x, col_y
table_name where col_z = 'yello'  limit k
col_z = 'yello'  limit k
null
===========

以上代码打印出以下输出

{
  "Emails": [
    "sample string 1",
    "sample string 2"
  ]
}

为什么资源组匹配器不会停在 where ？