THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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The following built-in type conversion functions are supported in Hive.
Return Type | Name(Signature) | Description |
|---|---|---|
binary | binary(string|binary) | Casts the parameter into a binary. |
Expected "=" to follow "type" | cast(expr as <type>) | Converts the results of the expression expr to <type>. For example, cast('1' as BIGINT) will convert the string '1' to its integral representation. A null is returned if the conversion does not succeed. If cast(expr as boolean) Hive returns true for a non-empty string. |
Conditional Functions
The following built-in conditional functions are supported in Hive.
Return Type | Name(Signature) | Description | |||||
|---|---|---|---|---|---|---|---|
T | if(boolean testCondition, T valueTrue, T valueFalseOrNull) | Returns valueTrue when testCondition is true, returns valueFalseOrNull otherwise. | |||||
| boolean | isnull( a ) | Returns true if a is NULL and false otherwise. | |||||
| boolean | isnotnull ( a ) | Returns true if a is not NULL and false otherwise. | |||||
| T | nvl(T value, T default_value) | Returns default value if value is null else returns value. | |||||
T | COALESCE(T v1, T v2, ...) | Returns the first v that is not NULL, or NULL if all v's are NULL. | |||||
T | CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END | When a = b, returns c; when a = d, returns e; else returns f. | |||||
T | CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END | When a = true, returns b; when c = true, returns d; else returns e. | |||||
| T | nullif( a, b ) | Returns NULL if a=b; otherwise returns a.
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| void | assert_true(boolean condition) | Throw an exception if 'condition' is not true, otherwise return null. For example, select assert_true (2<1). |
Data Masking Functions
Misc. Functions
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UDFs can be divided into three types depending on the number of input rows and the number of output rows returned. Each of these UDFs needs to derive (implement) a different interface.
| UDF | UDAF | UDTF |
|---|---|---|
| It is a function that receives only a single row as an input and returns a single row as an output. Like: length, or round functions Extend class: UDF | It is a function that receives multiple rows as input and returns a single row as output. Like: Count, Min, Max | It is a function that receives a single row as input and returns multiple rows - result set or table - as output. |