人大金仓数据库KingbaseES 新特性——mysql 支持的field函数

金仓数据库KingbaseES field 函数特性

关键字：

KingbaseES、mysql、string、field、人大金仓、KingbaseES

Kes在不同模式下的函数 field。

mysql 模式中，

兼容mysql的field(str, str1, str2, str3,…)函数。

函数定义：int field(any params)

函数功能：返回第一个参数值在剩余参数列表中的位置。如果没有找到则返回0。

• 如果只有一个参数则报错，错误信息是“Incorrect parameter count which must be more than one”；
• 如果第一个参数是null，则返回值是0；
• 如果所有参数都是同一类型，则按该类型进行比较；如果都是字符串类型（typcategory=S），则按字符串进行比较；如果所有参数都是数字(typcategory=N)，则按numeric类型进行比较；否则，参数按double类型进行比较（如果存在到double类型的转换，则调用转换函数进行处理；如果不存在，转为0值）。字符串比较不区分大小写。

最大输入参数个数为512。

filed在不同数据类型的实际差别

Mysql 模式

1. 不同类型 转换成double

select field(cast(2 as int8),'fa','>?>',2);

field

-------

3

(1 row)

2. 相同类型 按相同类型比较 这里都是字符串

select field('da','fr','daf','ree','da');--4

field

-------

4

(1 row)

3. 不相同的字符类型比较，注意比较的次序 是从左向右

select field('a', cast('a' as char),cast('b' as varchar),cast('2' as text));

field

-------

1

(1 row)

test=# select field('a', cast('aa' as char(1)),cast('b' as varchar),cast('a' as text));

field

-------

1

(1 row)

test=# select field('a', cast('aa' as char(2)),cast('b' as varchar),cast('a' as text));

field

-------

3

(1 row)

4. 不相同的数字类型比较

--数字类型

select field(2,cast(2 as int1),cast( 3 as int4 ),cast( 5 as int8 ),cast( 3 as middleint ),cast( 56 as real ),cast( 22 as float4 ),cast( 34.132 as float8 ),cast( 213 as fixed ),cast( 21 as middleint) );

field

-------

1

(1 row)

test=# select field(21,cast(2 as int1),cast( 3 as int4 ),cast( 5 as int8 ),cast( 3 as middleint ),cast( 56 as real ),cast( 22 as float4 ),cast( 34.132 as float8 ),cast( 213 as fixed ),cast( 21 as middleint) );

field

-------

9

(1 row)

test=#

--边界值验证 在超过512 个参数比较值 会直接报错

select field(1,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511);

field

-------

1

(1 row)

select field(32423,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511,512);

ksql:/tmp/tempdb/test/sql/mysql_func_field.sql:223: ERROR: cannot pass more than 512 arguments to a function

LINE 1: select field(32423,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17...