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Amazon Redshift
Database Developer Guide (API Version 2012-12-01)

LEAD Window Function

The LEAD window function returns the values for a row at a given offset below (after) the current row in the partition.

Syntax

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LEAD (value_expr [, offset ]) [ IGNORE NULLS | RESPECT NULLS ] OVER ( [ PARTITION BY window_partition ] ORDER BY window_ordering )

Arguments

value_expr

The target column or expression that the function operates on.

offset

An optional parameter that specifies the number of rows below the current row to return values for. The offset can be a constant integer or an expression that evaluates to an integer. If you do not specify an offset, Amazon Redshift uses 1 as the default value. An offset of 0 indicates the current row.

IGNORE NULLS

An optional specification that indicates that Amazon Redshift should skip null values in the determination of which row to use. Null values are included if IGNORE NULLS is not listed.

Note

You can use an NVL or COALESCE expression to replace the null values with another value. For more information, see NVL Expression.

RESPECT NULLS

Indicates that Amazon Redshift should include null values in the determination of which row to use. RESPECT NULLS is supported by default if you do not specify IGNORE NULLS.

OVER

Specifies the window partitioning and ordering. The OVER clause cannot contain a window frame specification.

PARTITION BY window_partition

An optional argument that sets the range of records for each group in the OVER clause.

ORDER BY window_ordering

Sorts the rows within each partition.

The LEAD window function supports expressions that use any of the Amazon Redshift data types. The return type is the same as the type of the value_expr.

Examples

See LEAD Window Function Examples.

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