SQL的一切常用函数展示

练习了一下，

用时再慢慢看吧。

SHOW WARNINGS;

SELECT quote(text_fld) FROM string_tbl;

SELECT CONCAT('danke sch', CHAR(148), 'n');

SELECT ASCII('ö');

SELECT LENGTH(char_fld) char_length FROM string_tbl;

SELECT POSITION('is' IN vchar_fld) FROM string_tbl;

SELECT (37 * 59) / (78 - (8 * 6));

SELECT MOD(10,4);

SELECT POW(2,10) kilobyte, POW(2,20) megabyte,
    -> POW(2,30) gigabyte, POW(2,40) terabyte;

SELECT ROUND(72.0909, 1), ROUND(72.0909, 2), ROUND(72.0909, 3);

SELECT account_id, SIGN(avail_balance), ABS(avail_balance)
    -> FROM account;

SELECT @@global.time_zone, @@session.time_zone;

SELECT CAST('2008-09-17 15:30:00' AS DATETIME);

SELECT CAST('2008-09-17' AS DATE) date_field,
    -> CAST('108:17:57' AS TIME) time_field;

SELECT CURRENT_DATE(), CURRENT_TIME(), CURRENT_TIMESTAMP();

SELECT DATE_ADD(CURRENT_DATE(), INTERVAL 5 DAY);

SELECT LAST_DAY('2008-09-17');

SELECT DAYNAME('2008-09-18');

SELECT EXTRACT(YEAR FROM '2008-09-18 22:19:05');

SELECT DATEDIFF('2009-09-03', '2009-06-24');

SELECT CAST('1456328' AS SIGNED INTEGER);

SELECT CAST('999ABC111' AS UNSIGNED INTEGER);