WHERE

WHERE clause allows to filter the data by specifying conditions.

Syntax

SELECT *
FROM table_name
WHERE condition;

If there is a WHERE clause, it must contain an expression with the Boolean type. This is usually an expression with comparison and logical operators. Rows where this expression evaluates to false are excluded from further transformations or result.

Examples

Logical operators

Supports AND, OR as logical operators and can assemble conditions using brackets ().

SELECT * FROM system_metrics
WHERE idc = 'idc0' AND (host = 'host1' OR host = 'host2');

Numeric

Supports =, !=, >, >=, <, <= as comparison operators.

SELECT * FROM system_metrics WHERE cpu_util = 20.0;
SELECT * FROM system_metrics WHERE cpu_util != 20.0;
SELECT * FROM system_metrics WHERE cpu_util > 20.0;
SELECT * FROM system_metrics WHERE cpu_util >= 20.0;
SELECT * FROM system_metrics WHERE cpu_util < 20.0;
SELECT * FROM system_metrics WHERE cpu_util <= 20.0;

List search

Evaluates match or mismatch against a list of elements.

List match

SELECT * FROM system_metrics WHERE idc IN ('idc_a', 'idc_b');

List mismatch

SELECT * FROM system_metrics WHERE idc NOT IN ('idc_a', 'idc_b');