John Davidson

Message:

i've a situation like the following :

• i've a long query that join a table


• all the columns in joined tabled contain a column 'name'. in this table there are two names 'A' and 'B' (but can be C,D......Z, i don't know how many names we can have) and both of them have multiple rows, so i've n rows with name A and n rows with name B


• sometimes, based on the user input, i need to join the entire table (with all the names) BUT only put some condition where the name is 'A' (for example).

so :

joint table myTable (it will take all the results A,B,C...)
but if the name = 'A'
then A.priority = A.userInput
(for B,C... get them without additional conditions)

so, is there a solutions for this or i need to do multiple calls to the database ?

Thanks.

---

My Answer:
You can achieve this by using a conditional WHERE clause in your SQL query. Here's an example query that demonstrates how you can achieve this:

php
$userInput = 'some_value'; // User input value

$sql = "SELECT *
FROM myTable
LEFT JOIN otherTable ON myTable.id = otherTable.myTableId
WHERE myTable.name <> 'A'
UNION
SELECT *
FROM myTable
LEFT JOIN otherTable ON myTable.id = otherTable.myTableId
WHERE myTable.name = 'A' AND A.priority = '$userInput'";

// Execute the query and fetch the results


In this query, we first select all rows where the name is not 'A' using `myTable.name <> 'A'`. Then, we use a `UNION` to combine the results with another query that selects rows where the name is 'A' and the priority is equal to the user input value.

This way, you can join the entire table but only apply the additional condition for rows where the name is 'A'. This should help you achieve the desired result without needing to make multiple calls to the database.