4.轉換函式:
---to_char
select to_char(hiredate,`yyyy-mm-dd`) from emp
select to_char (hiredate,`yyyy"年"mm"月"dd"日"`) from emp
select sal, to_char (sal, `l0,000,000.00`) as saltest from emp
結果:
查詢入職時間在1982年之後的員工:
select ename,hiredate from emp where hiredate>to_date(`1981-12-31`,`yyyy-mm-dd`)
查詢工資大於2000的所有員工:
select ename,sal from emp where sal>to_number(`¥2000`,`l9999`);
5.通用函式: