Returns the value that meets a specific condition in a map.

Usage notes

  • If var1 is of the map<K, V> type, this function obtains the element that is at position var2 in var1. The position numbers of elements are counted from left to right and start from 0.
  • If var1 is of the map<K, V> type, this function obtains the value whose key is var2 in var1.
Note When you use this function, you must remove index and directly execute <var1>[<var2>]. Otherwise, an error is returned.

Syntax

index(<var1>[<var2>])

Parameters

  • var1: required. The value must be of the array<T> or map<K, V> type. T in array<T> specifies the data type of the elements in an array. The elements can be of any data type. K and V in map<K, V> specify the keys and values of a map.
  • var2: required.
    • If var1 is of the array<T> type, var2 must be of the BIGINT type and greater than or equal to 0.
    • If var1 is of the map<K, V> type, var2 must be of the same data type as K.

Return value

  • If var1 is of the array<T> type, a value of the data type that is specified by T is returned. The return value varies based on the following rules:
    • If the number of elements in var1 is less than var2, null is returned.
    • If var1 is null, null is returned.
  • If var1 is of the map<K, V> type, a value that is of the same data type as V is returned. The return value varies based on the following rules:
    • If map<K, V> does not contain a key whose value is var2, null is returned.
    • If var1 is null, null is returned.

Examples

  • Example 1: var1 is of the array<T> type. Sample statement: 
    -- c is returned. 
select array('a','b','c')[2];
  • Example 2: var1 is of the map<K, V> type. Sample statement: 
    -- The value 1 is returned. 
select str_to_map("test1=1,test2=2")["test1"];