使用特定格式的字段查询

Question

I have an SQL table with a field REFERENCE . Most of the references are like this: A123B45* I mean:

1 letter, 3 digits, 1 letter, 2 digits, anything

But some are different , like AB123C12 they start by 2 letters.

I want to make a query to get only the lines with a reference corresponding to the first example A123B45* .

I already tried this:

select REFERENCE from facture where REFERENCE REGEXP "[a-zA-Z][0-9]{3}[a-zA-Z][0-9]{2}[.]*"

But this doesn't work because I have also lines starting by two letters .

Answer 1

Add ^ anchor , since reference must start from (not contain ) the regular expression:

    select REFERENCE 
      from facture 
     where REFERENCE REGEXP "^[a-zA-Z][0-9]{3}[a-zA-Z][0-9]{2}"

What's going on:

   AB123C12 <-- doesn't start from the pattern 
    ^     ^
    |-----| <-- but contains the pattern  

that's why you had false positives