title: joining tables with different length column values
body: <p>I need to get ID by joining columns of tables with variable length.
  Table A has 2 columns ID and PostCode</p>
  
  <pre>
  -----------------
  | ID | PostCode |
  |----|----------|
  | 1  |    BR    |
  |----|----------|
  | 2  |    WT    |
  |----|----------|
  | 3  |    B71   |
  |----|----------|
  | 4  |    BR5   |
  |----|----------|
  </pre>
  
  <p>Table B has columns with Name and Full postcode</p>
  
  <pre>
  |------|----------|
  | Name | PostCode |
  |------|----------|
  | Mr X | CR2  5ER |
  |------|----------|
  | Ms Y | BT2  6ER |
  |------|----------|
  | XX   | B71  4WQ |
  |------|----------|
  | YY   | BR4  8ER |
  |------|----------|
  | SS   | BR5A 5RT |
  |------|----------|
  </pre>
  
  <p>I need to get Id's 1 [BR->BR4 8ER], 3 [B71->B71 4WQ] and 4 [BR5->BR5A 5RT]
  How do I get to work this?</p>