Databases
StackOverflow2013
Postsdbo
POFilter Table Before Applying Left Join
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POFilter Table Before Applying Left Join
    primarykey
    data
    text
    <p>I have 2 tables, I want to filter the 1 table <strong>before</strong> the 2 tables are joined together.</p> <p>Customer Table:</p> <pre><code> ╔══════════╦═══════╗ ║ Customer ║ State ║ ╠══════════╬═══════╣ ║ A ║ S ║ ║ B ║ V ║ ║ C ║ L ║ ╚══════════╩═══════╝ </code></pre> <p>Entry Table:</p> <pre><code> ╔══════════╦═══════╦══════════╗ ║ Customer ║ Entry ║ Category ║ ╠══════════╬═══════╬══════════╣ ║ A ║ 5575 ║ D ║ ║ A ║ 6532 ║ C ║ ║ A ║ 3215 ║ D ║ ║ A ║ 5645 ║ M ║ ║ B ║ 3331 ║ A ║ ║ B ║ 4445 ║ D ║ ╚══════════╩═══════╩══════════╝ </code></pre> <p>OK I want to Left Join so I get all records from the Customer table regardless of whether there are related records in the Entry table. However I want to filter on category D in the entry table <strong>before the join</strong>.</p> <p>Desired Results:</p> <pre><code> ╔══════════╦═══════╦═══════╗ ║ Customer ║ State ║ Entry ║ ╠══════════╬═══════╬═══════╣ ║ A ║ S ║ 5575 ║ ║ A ║ S ║ 3215 ║ ║ B ║ A ║ 4445 ║ ║ C ║ L ║ NULL ║ ╚══════════╩═══════╩═══════╝ </code></pre> <p>If I was to do the following query:</p> <pre><code> SELECT Customer.Customer, Customer.State, Entry.Entry FROM Customer LEFT JOIN Entry ON Customer.Customer=Entry.Customer WHERE Entry.Category='D' </code></pre> <p>This would filter out the last record.</p> <p>So I want all rows from the left table, and join it to the entry table filtered on category D.</p> <p>Thanks to any help in advance!!</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USTom Jenkin
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POFilter Table Before Applying Left Join
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POFilter Table Before Applying Left Join
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POFilter Table Before Applying Left Join
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload