decode (expression, search_1, result_1), A8 n b9 v2 _+ @/ \7 _4 U( `. r7 K
如果 expression结果=search_1结果,则返回result_13 P$ l7 V6 k+ [5 X; c0 l& Y
decode (expression, search_1, result_1, search_2, result_2)" k/ b: w5 b1 R( c. A
decode (expression, search_1, result_1, search_2, result_2, ...., search_n, result_n) a( y1 q( L5 d/ _9 Z
decode (expression, search_1, result_1, default)
7 k! O. o% e, V 如果 expression结果=search_1结果,则返回result_1,否则反回default6 o7 c# o* t1 G# u4 b# O
decode (expression, search_1, result_1, search_2, result_2, default)8 g* u! y! {9 O$ h% ^4 N: T0 a
decode (expression, search_1, result_1, search_2, result_2, ...., search_n, result_n, default)
) @( z/ ^# Z& S, O decode函数比较表达式和搜索字,如果匹配,返回结果;如果不匹配,返回default值;如果未定义default值,则返回空值。! a5 ~* N* \+ ~8 n9 R: L
如:& q( f/ ]: J4 S8 }! l" P" ?" m
select (a/b*100) as percent from t& w# q5 n4 V4 w0 R2 j: f- D
如果b为0会出现被除数为00 }8 R. ]; [" e4 ]# x
解决:
0 m3 r, S: T4 Q' g9 i5 G select decode(b,0,0,a/b*100) as percent from t |