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concat function

The concat() and concat_ws() functions return strings concatenated by one or more strings.

concat() function

The concat() function requires at least two or more strings. All the parameters are concatenated into one string.

  • If there is only one string, the string itself is returned.
  • If any one of the strings is NULL, NULL is returned.

Syntax

concat(string1,string2,...)

Examples

//This example concatenates 1, 2, and 3.
nebula> RETURN concat("1","2","3") AS r;
+-------+
| r     |
+-------+
| "123" |
+-------+

//In this example, one of the string is 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() function

The concat_ws() function connects two or more strings with a predefined separator.

  • If the separator is NULL, the concat_ws() function returns NULL.
  • If the separator is not NULL and there is only one string, the string itself is returned.
  • If the separator is not NULL and there is a NULL in the strings, NULL is ignored during the concatenation.

Syntax

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

Examples

//This example concatenates a, b, and c with the separator +.
nebula> RETURN concat_ws("+","a","b","c") AS r;
+---------+
| r       |
+---------+
| "a+b+c" |
+---------+

//In this example, the separator is NULL.
neubla> RETURN concat_ws(NULL,"a","b","c") AS r;
+----------+
| r        |
+----------+
| __NULL__ |
+----------+

//In this example, the separator is + and there is a NULL in the strings.
nebula> RETURN concat_ws("+","a",NULL,"b","c") AS r;
+---------+
| r       |
+---------+
| "a+b+c" |
+---------+

//In this example, the separator is + and there is only one string.
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" |
+---------------------------------+
Last update: September 13, 2021
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