SQL
Conjunctions
The `AND`/`OR` conjunctions can be used to combine Boolean values.  
Below is the truth table for the `AND` conjunction (i.e., `x AND y`).  
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|  X  | X AND true  | X AND false | X AND NULL  |
|-------|-------|-------|-------|
| true  | true  | false | NULL  |
| false | false | false | false |
| NULL  | NULL  | false | NULL  |  
Below is the truth table for the `OR` conjunction (i.e., `x OR y`).  
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|  X   | X OR true | X OR false | X OR NULL |
|-------|------|-------|------|
| true  | true | true  | true |
| false | true | false | NULL |
| NULL  | true | NULL  | NULL |