WHERE
WHERE clause allows to filter the data by specifying conditions.
Syntax
sql
SELECT *
FROM table_name
WHERE condition;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 ().
sql
SELECT * FROM system_metrics
WHERE idc = 'idc0' AND (host = 'host1' OR host = 'host2');SELECT * FROM system_metrics
WHERE idc = 'idc0' AND (host = 'host1' OR host = 'host2');Numeric
Supports =, !=, >, >=, <, <= as comparison operators.
sql
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;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
sql
SELECT * FROM system_metrics WHERE idc IN ('idc_a', 'idc_b');SELECT * FROM system_metrics WHERE idc IN ('idc_a', 'idc_b');List mismatch
sql
SELECT * FROM system_metrics WHERE idc NOT IN ('idc_a', 'idc_b');SELECT * FROM system_metrics WHERE idc NOT IN ('idc_a', 'idc_b');