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spark-instrumented-optimizer/docs/sql-ref-syntax-qry-select-like.md
Huaxin Gao d34cb59fb3 [SPARK-31556][SQL][DOCS] Document LIKE clause in SQL Reference 
### What changes were proposed in this pull request?
Document LIKE clause in SQL Reference

### Why are the changes needed?
To make SQL Reference complete

### Does this PR introduce any user-facing change?
Yes

<img width="1050" alt="Screen Shot 2020-04-25 at 5 49 57 PM" src="https://user-images.githubusercontent.com/13592258/80294346-5babab80-871d-11ea-8ac9-51bbab0aca88.png">

<img width="1050" alt="Screen Shot 2020-04-25 at 5 50 24 PM" src="https://user-images.githubusercontent.com/13592258/80294347-5ea69c00-871d-11ea-8c51-7a90ee20f7da.png">

<img width="1050" alt="Screen Shot 2020-04-25 at 5 50 42 PM" src="https://user-images.githubusercontent.com/13592258/80294351-61a18c80-871d-11ea-9e75-e3345d2f52f5.png">

### How was this patch tested?
Manually build and check

Closes #28332 from huaxingao/where_clause.

Authored-by: Huaxin Gao <huaxing@us.ibm.com>
Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
2020-04-29 09:17:23 +09:00

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global LIKE Predicate LIKE Predicate Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Description

A LIKE predicate is used to search for a specific pattern.

Syntax

{% highlight sql %} [ NOT ] { LIKE search_pattern [ ESCAPE esc_char ] | RLIKE regex_pattern } {% endhighlight %}

Parameters

search_pattern
Specifies a string pattern to be searched by the LIKE clause. It can contain special pattern-matching characters:
  • %
    • matches zero or more characters.
  • _
    • matches exactly one character.
esc_char
Specifies the escape character. The default escape character is \.
regex_pattern
Specifies a regular expression search pattern to be searched by the RLIKE clause.

Examples

{% highlight sql %} CREATE TABLE person (id INT, name STRING, age INT); INSERT INTO person VALUES (100, 'John', 30), (200, 'Mary', NULL), (300, 'Mike', 80), (400, 'Dan', 50), (500, 'Evan_w', 16);

SELECT * FROM person WHERE name LIKE 'M%'; +---+----+----+ | id|name| age| +---+----+----+ |300|Mike| 80| |200|Mary|null| +---+----+----+

SELECT * FROM person WHERE name LIKE 'M_ry'; +---+----+----+ | id|name| age| +---+----+----+ |200|Mary|null| +---+----+----+

SELECT * FROM person WHERE name NOT LIKE 'M_ry'; +---+------+---+ | id| name|age| +---+------+---+ |500|Evan_W| 16| |300| Mike| 80| |100| John| 30| |400| Dan| 50| +---+------+---+

SELECT * FROM person WHERE name RLIKE '[MD]'; +---+----+----+ | id|name| age| +---+----+----+ |300|Mike| 80| |400| Dan| 50| |200|Mary|null| +---+----+----+

SELECT * FROM person WHERE name LIKE '%_%'; +---+------+---+ | id| name|age| +---+------+---+ |500|Evan_W| 16| +---+------+---+

SELECT * FROM person WHERE name LIKE '%$_%' ESCAPE '$'; +---+------+---+ | id| name|age| +---+------+---+ |500|Evan_W| 16| +---+------+---+ {% endhighlight %}

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