Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
SQL
FULL OUTER JOIN / CROSS JOIN
`FULL OUTER` keeps unmatched rows from BOTH sides. `CROSS JOIN` is the Cartesian product — every row of A paired with every row of B. Rare but useful for date-spine and matrix generation.
@admin
SQL
LEFT JOIN — Keep Unmatched Left Rows
Returns every row from the LEFT side, NULL-filled where the right side doesn't match. The standard pattern for "this entity and its optional children".
SQL
Self-Join — Org Chart / Hierarchies
A self-join is just a regular join with the same table aliased twice. The canonical example is an employee table where each row points to a manager in the same table.