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[DOCS] SQL: Document null handing for string functions #74201

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Jun 16, 2021
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[DOCS] SQL: Document null handing for string functions #74201

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70 changes: 36 additions & 34 deletions docs/reference/sql/functions/string.asciidoc
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ ASCII(string_exp) <1>

*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand All @@ -37,7 +37,7 @@ BIT_LENGTH(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand All @@ -58,7 +58,7 @@ CHAR(code) <1>
--------------------------------------------------
*Input*:

<1> integer expression
<1> integer expression. If `null` or negative, the function returns `null`.

*Output*: string

Expand All @@ -79,7 +79,7 @@ CHAR_LENGTH(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand Down Expand Up @@ -107,7 +107,7 @@ CONCAT(

*Output*: string

*Description*: Returns a character string that is the result of concatenating `string_exp1` to `string_exp2`. `NULL` input strings are treated as empty strings.
*Description*: Returns a character string that is the result of concatenating `string_exp1` to `string_exp2`. `null` input strings are treated as empty strings.

[source, sql]
--------------------------------------------------
Expand All @@ -128,10 +128,10 @@ INSERT(
--------------------------------------------------
*Input*:

<1> string expression
<2> integer expression
<3> integer expression
<4> string expression
<1> string expression. If `null`, the function returns `null`.
<2> integer expression. If `null`, the function returns `null`.
<3> integer expression. If `null`, the function returns `null`.
<4> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -152,7 +152,7 @@ LCASE(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -175,8 +175,9 @@ LEFT(
--------------------------------------------------
*Input*:

<1> string expression
<2> integer expression
<1> string expression. If `null`, the function returns `null`.
<2> integer expression. If `null`, the function returns `null`. If `0` or
negative, the function returns an empty string.

*Output*: string

Expand All @@ -197,7 +198,7 @@ LENGTH(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand Down Expand Up @@ -228,7 +229,7 @@ LOCATE(

*Output*: integer

*Description*: Returns the starting position of the first occurrence of `pattern` within `source`. The optional `start` specifies the character position to start the search with. The first character position in `source` is indicated by the value 1. Not specifying `start` or specifying it as `NULL`, any negative value, 0 or 1, starts the search at the first character position. If `pattern` is not found within `source`, the value 0 is returned.
*Description*: Returns the starting position of the first occurrence of `pattern` within `source`. The optional `start` specifies the character position to start the search with. The first character position in `source` is indicated by the value 1. Not specifying `start` or specifying it as `null`, any negative value, 0 or 1, starts the search at the first character position. If `pattern` is not found within `source`, the value 0 is returned.

[source, sql]
--------------------------------------------------
Expand All @@ -250,7 +251,7 @@ LTRIM(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -271,7 +272,7 @@ OCTET_LENGTH(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand All @@ -294,8 +295,8 @@ POSITION(
--------------------------------------------------
*Input*:

<1> string expression
<2> string expression
<1> string expression. If `null`, the function returns `null`.
<2> string expression. If `null`, the function returns `null`.

*Output*: integer

Expand All @@ -318,8 +319,8 @@ REPEAT(
--------------------------------------------------
*Input*:

<1> string expression
<2> integer expression
<1> string expression. If `null`, the function returns `null`.
<2> integer expression. If `0`, negative, or `null`, the function returns `null`.

*Output*: string

Expand All @@ -343,9 +344,9 @@ REPLACE(
--------------------------------------------------
*Input*:

<1> string expression
<2> string expression
<3> string expression
<1> string expression. If `null`, the function returns `null`.
<2> string expression. If `null`, the function returns `null`.
<3> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -368,8 +369,9 @@ RIGHT(
--------------------------------------------------
*Input*:

<1> string expression
<2> integer expression
<1> string expression. If `null`, the function returns `null`.
<2> integer expression. If `null`, the function returns `null`. If `0` or
negative, the function returns an empty string.

*Output*: string

Expand All @@ -390,7 +392,7 @@ RTRIM(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -411,7 +413,7 @@ SPACE(count) <1>
--------------------------------------------------
*Input*:

<1> integer expression
<1> integer expression. If `null` or negative, the function returns `null`.

*Output*: string

Expand All @@ -434,8 +436,8 @@ STARTS_WITH(
--------------------------------------------------
*Input*:

<1> string expression
<2> string expression
<1> string expression. If `null`, the function returns `null`.
<2> string expression. If `null`, the function returns `null`.

*Output*: boolean value

Expand Down Expand Up @@ -465,9 +467,9 @@ SUBSTRING(
--------------------------------------------------
*Input*:

<1> string expression
<2> integer expression
<3> integer expression
<1> string expression. If `null`, the function returns `null`.
<2> integer expression. If `null`, the function returns `null`.
<3> integer expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -487,7 +489,7 @@ TRIM(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: string

Expand All @@ -508,7 +510,7 @@ UCASE(string_exp) <1>
--------------------------------------------------
*Input*:

<1> string expression
<1> string expression. If `null`, the function returns `null`.

*Output*: string

Expand Down