Hive

This chapter explains the built-in operators of Hive. There are four types of operators in Hive:

• Relational Operators：关系操作
• Arithmetic Operators
• Logical Operators
• Complex Operators：比较复杂的是这个，目前博主还没有实际玩过这个，在hue中体验了一把，还是挺好玩的。http://demo.gethue.com

Relational Operators

These operators are used to compare two operands. The following table describes the relational operators available in Hive:

Operator	Operand	Description
A = B	all primitive types	TRUE if expression A is equivalent to expression B otherwise FALSE.
A != B	all primitive types	TRUE if expression A is not equivalent to expression B otherwise FALSE.
A < B	all primitive types	TRUE if expression A is less than expression B otherwise FALSE.
A <= B	all primitive types	TRUE if expression A is less than or equal to expression B otherwise FALSE.
A > B	all primitive types	TRUE if expression A is greater than expression B otherwise FALSE.
A >= B	all primitive types	TRUE if expression A is greater than or equal to expression B otherwise FALSE.
A IS NULL	all types	TRUE if expression A evaluates to NULL otherwise FALSE.
A IS NOT NULL	all types	FALSE if expression A evaluates to NULL otherwise TRUE.
A LIKE B	Strings	TRUE if string pattern A matches to B otherwise FALSE.
A RLIKE B	Strings	NULL if A or B is NULL, TRUE if any substring of A matches the Java regular expression B , otherwise FALSE.
A REGEXP B	Strings	Same as RLIKE.

Example

Let us assume the employee table is composed of fields named Id, Name, Salary, Designation, and Dept as shown below. Generate a query to retrieve the employee details whose Id is 1205.

+-----+--------------+--------+---------------------------+------+
| Id  | Name         | Salary | Designation               | Dept |
+-----+--------------+------------------------------------+------+
|1201 | Gopal        | 45000  | Technical manager         | TP   |
|1202 | Manisha      | 45000  | Proofreader               | PR   |
|1203 | Masthanvali  | 40000  | Technical writer          | TP   |
|1204 | Krian        | 40000  | Hr Admin                  | HR   |
|1205 | Kranthi      | 30000  | Op Admin                  | Admin|
+-----+--------------+--------+---------------------------+------+

The following query is executed to retrieve the employee details using the above table:

hive> SELECT * FROM employee WHERE Id=1205;

On successful execution of query, you get to see the following response:

+-----+-----------+-----------+----------------------------------+
| ID  | Name      | Salary    | Designation              | Dept  |
+-----+---------------+-------+----------------------------------+
|1205 | Kranthi   | 30000     | Op Admin                 | Admin |
+-----+-----------+-----------+----------------------------------+

The following query is executed to retrieve the employee details whose salary is more than or equal to Rs 40000.

hive> SELECT * FROM employee WHERE Salary>=40000;

On successful execution of query, you get to see the following response:

+-----+------------+--------+----------------------------+------+
| ID  | Name       | Salary | Designation                | Dept |
+-----+------------+--------+----------------------------+------+
|1201 | Gopal      | 45000  | Technical manager          | TP   |
|1202 | Manisha    | 45000  | Proofreader                | PR   |
|1203 | Masthanvali| 40000  | Technical writer           | TP   |
|1204 | Krian      | 40000  | Hr Admin                   | HR   |
+-----+------------+--------+----------------------------+------+

Arithmetic Operators

These operators support various common arithmetic operations on the operands. All of them return number types. The following table describes the arithmetic operators available in Hive:

Operators	Operand	Description
A + B	all number types	Gives the result of adding A and B.
A - B	all number types	Gives the result of subtracting B from A.
A * B	all number types	Gives the result of multiplying A and B.
A / B	all number types	Gives the result of dividing B from A.
A % B	all number types	Gives the reminder resulting from dividing A by B.
A & B	all number types	Gives the result of bitwise AND of A and B.
A | B	all number types	Gives the result of bitwise OR of A and B.
A ^ B	all number types	Gives the result of bitwise XOR of A and B.
~A	all number types	Gives the result of bitwise NOT of A.

Example

The following query adds two numbers, 20 and 30.

hive> SELECT 20+30 ADD FROM temp;

On successful execution of the query, you get to see the following response:

+--------+
|   ADD  |
+--------+
|   50   |
+--------+

Logical Operators

The operators are logical expressions. All of them return either TRUE or FALSE.

Operators	Operands	Description
A AND B	boolean	TRUE if both A and B are TRUE, otherwise FALSE.
A && B	boolean	Same as A AND B.
A OR B	boolean	TRUE if either A or B or both are TRUE, otherwise FALSE.
A || B	boolean	Same as A OR B.
NOT A	boolean	TRUE if A is FALSE, otherwise FALSE.
!A	boolean	Same as NOT A.

Example

The following query is used to retrieve employee details whose Department is TP and Salary is more than Rs 40000.

hive> SELECT * FROM employee WHERE Salary>40000 && Dept=TP;

On successful execution of the query, you get to see the following response:

+------+--------------+-------------+-------------------+--------+
| ID   | Name         | Salary      | Designation       | Dept   |
+------+--------------+-------------+-------------------+--------+
|1201  | Gopal        | 45000       | Technical manager | TP     |
+------+--------------+-------------+-------------------+--------+

Complex Operators 

These operators provide an expression to access the elements of Complex Types.

Operator	Operand	Description
A[n]	A is an Array and n is an int	It returns the nth element in the array A. The first element has index 0.
M[key]	M is a Map<K, V> and key has type K	It returns the value corresponding to the key in the map.
S.x	S is a struct	It returns the x field of S.

译注：这块本人还没有实际玩过，就找一个demo：http://demo.gethue.com/

-- 查询中包含了Map，Struct类型的两个字段查询
select addresses["shipping"],email_preferences.email_format from customers  ;

--- 其实HUE还是很智能的，提示很给力！

 

-----------

英文地址：https://www.tutorialspoint.com/hive/hive_built_in_operators.htm