COUNT DISTINCT

Syntax

COUNT(DISTINCT expr,[expr...])

Description

Returns a count of the number of different non-NULL values.

COUNT(DISTINCT) returns 0 if there were no matching rows.

Examples

CREATE TABLE student (name CHAR(10), test CHAR(10), score TINYINT);   INSERT INTO student VALUES   ('Chun', 'SQL', 75), ('Chun', 'Tuning', 73),   ('Esben', 'SQL', 43), ('Esben', 'Tuning', 31),   ('Kaolin', 'SQL', 56), ('Kaolin', 'Tuning', 88),   ('Tatiana', 'SQL', 87), ('Tatiana', 'Tuning', 83);  SELECT COUNT(*) FROM student; +----------+ | COUNT(*) | +----------+ | 8 | +----------+  SELECT COUNT(DISTINCT (name)) FROM student; +------------------------+ | COUNT(DISTINCT (name)) | +------------------------+ | 4 | +------------------------+

See Also

• SELECT

• COUNT

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