# SQL Expression

By | October 2, 2021 When we use two or more than two combinations of values, operators and SQL functions, then it is considered as an expression. We write an expression as a statement or query which act as a formula to show some output. We often use various expressions to query a database.

### Expression Syntax

```SELECT column_name_1, column_name_2, column_name_N
FROM table_name
WHERE [EXPRESSION];```

We can apply expression on Different data types which include:

• Boolean
• Numeric
• Date

### Boolean Expression

In boolean expression we write expression on the basis of the boolean values 0(true) and 1 (false), and we get only true values as query result.

Syntax

```SELECT column_name_1, column_name_2, column_name_N
FROM table_name
WHERE value match [boolean EXPRESSION];```

Example

Consider this table as Students:

```+----+----------+-----+-------+------+
|Rank| NAME     | AGE | Grade | Marks|
+----+----------+-----+-------+------+
|  1 | Luffy    |  18 | A     |  976 |
|  2 | Naruto   |  16 | A     |  970 |
|  3 | Goku     |  20 | A     |  970 |
|  4 | Zoro     |  26| B      |  890 |
|  5 | Asta     |  16 | B     |  860 |
|  6 | Robin    |  24 |B      |  850 |
|  7 | Gohan    |  18 | C     |  845 |
+----+----------+-----+-------+------+```
`SELECT * FROM Students WHERE marks = 970;`

Output

```+----+----------+-----+-----------+----------+
|Rank|  NAME    | AGE | Grade     | Marks    |
+----+----------+-----+-----------+----------+
|  2 | Naruto   |  16 | A         |  970     |
|  3 | Goku     |  20 | A         |  970     |
+----+----------+-----+-----------+----------+```

### Numeric Expression

We use Numeric Expression to perform the Arithmetic Operations.

Syntax

`SELECT Numeric_Expression AS Custom_Column_Name;`

Example

`SELECT (17+20) AS add;`

Output

``` +----------+
+----------+
|       37 |
+----------+```

### Date Expression

Date Expression are used to show the time and date related outputs.

Example

`select CURRENT_TIMESTAMP;`

Output

```+---------------------+
| CURRENT_TIMESTAMP   |
+---------------------
| 2020-03-29 13:38:43 |
+---------------------+
1 row in set (0.05 sec)```

### SQL Expression Quick Summary

• An expression is a query statement that is a combination of one or more than one value, Operators and SQL Functions.
• In SQL we have 3 major Expressions, Boolean, Numeric and Date.
• Boolean Expression deals with the logical and comparison operators where we have results in true and false.
• Numeric Expressions work with Arithmetic Operators.
• Date Expression Work with Date and time data types.