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concat函数

concat()concat_ws()函数返回一个或多个字符串连接产生的字符串。

Enterpriseonly

仅企业版支持本功能。

concat()函数

concat()函数至少需要两个或以上字符串参数,并将所有参数连接成一个字符串。

  • 如果字符串参数只有一个,则返回该字符串参数本身。
  • 如果任何一个的字符串参数为 NULL,则 concat() 函数返回值为NULL

语法

concat(string1,string2,...)

示例

//连接1,2,3
nebula> RETURN concat("1","2","3") AS r;
+-------+
| r     |
+-------+
| "123" |
+-------+

//字符串参数有NULL
nebula> RETURN concat("1","2",NULL) AS r;
+----------+
| r        |
+----------+
| __NULL__ |
+----------+

nebula> GO FROM "player100" over follow \
        YIELD concat(follow._src, $^.player.age, $$.player.name, follow.degree) AS A;
+------------------------------+
| A                            |
+------------------------------+
| "player10042Tony Parker95"   |
+------------------------------+
| "player10042Manu Ginobili95" |
+------------------------------+

concat_ws()函数

concat_ws()函数将两个或以上字符串参数与预定义的分隔符(separator)相连接。

  • 如果分隔符为NULL时,concat_ws()函数才返回NULL
  • 如果分隔符不为NULL,字符串参数只有一个,则返回该字符串参数本身。
  • 字符串参数存在NULL值时,忽略NULL值,继续连接下一个参数。

语法

concat_ws(separator,string1,string2,... )

示例

//分隔符为+,连接a,b,c
nebula> RETURN concat_ws("+","a","b","c") AS r;
+---------+
| r       |
+---------+
| "a+b+c" |
+---------+

//分隔符为 NULL
neubla> RETURN concat_ws(NULL,"a","b","c") AS r;
+----------+
| r        |
+----------+
| __NULL__ |
+----------+

//分隔符为+,字符串参数有NULL
nebula> RETURN concat_ws("+","a",NULL,"b","c") AS r;
+---------+
| r       |
+---------+
| "a+b+c" |
+---------+

//分隔符为+。字符串参数只有一个
nebula> RETURN concat_ws("+","a") AS r;
+-----+
| r   |
+-----+
| "a" |
+-----+

nebula> GO FROM "player100" over follow \
        YIELD concat_ws(" ",follow._src, $^.player.age, $$.player.name, follow.degree) AS A;
+---------------------------------+
| A                               |
+---------------------------------+
| "player100 42 Tony Parker 95"   |
+---------------------------------+
| "player100 42 Manu Ginobili 95" |
+---------------------------------+

最后更新: September 14, 2021
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