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SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Guide to SQL: Syntax
The Informix® Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the Informix dialect of the SQL language.
Data types and expressions
These topics describe the data types and expressions that Informix®supports.
OLAP window expressions
You can include On-Line Analytical Processing (OLAP) expressions in a SELECT statement to operate on subsets of the rows in the result set of a query or subquery. You can use OLAP window expressions to examine subsets of the qualifying rows for patterns, trends, or exceptions in the data.
OLAP ranking function expressions
You can include OLAP ranking function expressions to calculate ordinal ranks that can be applied to each row in the partitioned result set of a query or subquery.

SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
- Guide to SQL: Syntax
  The Informix® Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the Informix dialect of the SQL language.
  - Overview of SQL syntax
    These topics provide an overview about how to use the SQL statements, SPL statements, and syntax segments.
  - SQL statements
    This chapter describes the syntax and semantics of SQL statements that are recognized by Informix®.
  - SPL statements
    These topics describe Stored Procedure Language (SPL) statements, which you use to write SPL routines. You can store these routines in the database as user-defined routines (UDRs).
  - Data types and expressions
    These topics describe the data types and expressions that Informix®supports.
    - Scope of Segment Descriptions
    - Use of Segment Descriptions
    - Data type and expression segments
      Data type and expression segments can appear in SQL statements.
    - Collection Subquery
    - Condition
    - Data Type
      The Data Type segment specifies the data type of a column, of a component of a collection, of a field within a ROW type, of a routine parameter, or of a value returned by an expression or by a cast function. Use this segment whenever you see a reference to a data type in a syntax diagram.
    - DATETIME Field Qualifier
      Use a DATETIME Field Qualifier to specify the largest and smallest unit of time in a DATETIME column or value. Use this segment whenever you see a reference to a DATETIME Field Qualifier in a syntax diagram.
    - Expression
    - OLAP window expressions
      You can include On-Line Analytical Processing (OLAP) expressions in a SELECT statement to operate on subsets of the rows in the result set of a query or subquery. You can use OLAP window expressions to examine subsets of the qualifying rows for patterns, trends, or exceptions in the data.
      - OLAP numbering function expression
        The OLAP numbering function expression returns a sequential number for each row in the result set of a single query.
      - OLAP ranking function expressions
        You can include OLAP ranking function expressions to calculate ordinal ranks that can be applied to each row in the partitioned result set of a query or subquery.
        LAG and LEAD functions
        The LAG and LEAD functions are OLAP ranking functions that return the value of their expression argument for the row at a specified offset from the current row within the current window partition.
        RANK function
        The RANK function is an OLAP ranking function that calculates a ranking value for each row in an OLAP window. The return value is an ordinal number, which is based on the required ORDER BY expression in the OVER clause.
        DENSE_RANK function
        The DENSE_RANK function is an OLAP ranking function that calculates a ranking value for each row in an OLAP window. The return value is an ordinal number, which is based on the required ORDER BY expression in the OVER clause.
        PERCENT_RANK function
        The PERCENT_RANK function is an OLAP ranking function that calculates a ranking value for each row in an OLAP window, normalized to a range from 0 to 1.
        CUME_DIST function
        The CUME_DIST function is an OLAP ranking function that calculates a cumulative distribution as a percentile ranking for each row. The rank is expressed as a decimal fraction that ranges from 0 to 1.
        NTILE function
        The NTILE function is an OLAP ranking function that classifies the rows in each partition into N ranked categories, called tiles, where each category includes an approximately equal number of rows.
      - OLAP aggregation function expressions
        OLAP aggregation function expressions can return aggregate information about rows in the partitioned results of a query.
      - OVER clause for OLAP window expressions
        The OVER clause defines the result set on which an OLAP window expression is performed.
    - INTERVAL Field Qualifier
    - Literal Collection
    - Literal DATETIME
      The Literal DATETIME segment specifies a DATETIME value
    - Literal INTERVAL
      The Literal INTERVAL segment specifies a literal INTERVAL value. Use this whenever you see a reference to a literal INTERVAL in a syntax diagram.
    - Literal Number
    - Literal Row
      The Literal Row segment specifies the syntax for literal values of named and unnamed ROW data types.
    - Quoted String
    - Relational Operator
  - Other syntax segments
    These topics describe syntax segments, which are language elements, such as database object names or optimizer directives, that appear as a subdiagram reference in the syntax diagrams of some SQL or SPL statements.
  - Built-In Routines
  - Appendixes
- Guide to SQL: Reference
  The Informix® Guide to SQL: Reference contains the reference information for the system catalog tables, data types, and environment variables of the HCL Informix dialect of the SQL language, as implemented in HCL Informix. These topics also include information about the stores_demo, sales_demo, and superstore_demo databases that are included with HCL Informix.
- Guide to SQL: Tutorial
  The Informix® Guide to SQL: Tutorial shows how to use basic and advanced structured query language (SQL) to access and manipulate the data in your databases. It discusses the data manipulation language (DML) statements as well as triggers and stored procedure language (SPL) routines, which DML statements often use.

OLAP ranking function expressions

You can include OLAP ranking function expressions to calculate ordinal ranks that can be applied to each row in the partitioned result set of a query or subquery.

OLAP ranking function expressions are OLAP window expressions that you can include in the Projection list of a SELECT statement, or the ORDER BY clause of a SELECT statement.

Syntax

^{(explicit id orfl001)
orfl001} ^{(explicit id orfl006)
orfl006} ^{(explicit id orfl002)
orfl002} ^{(explicit id orfl003)
orfl003} ^{(explicit id orfl004)
orfl004} ^{(explicit id orfl005)
orfl005} ^{(explicit id orfl007)
orfl007}

OLAP ranking function expressions

<OLAP ranking function><OVER clause for ranking functions>

OLAP ranking function

{ <LAG function>^[] | <LEAD function> ^[] | <RANK function>^[] | <DENSE_RANK function>^[] | <PERCENT_RANK function>^[] | <CUME_DIST function>^[] | <NTILE function>^[] }

OVER clause for ranking functions

OVER(<Window PARTITION clause>^[] <Window ORDER clause>^[])

Usage

The ranking values that these functions return are dependent on the window ORDER clause within the OVER clause. The ORDER clause defines the columns or expressions that the database server uses to calculate the ranking values.

If you omit the window PARTITION clause, the scope of the ranking function is the entire result set of the query or subquery, rather than partitioned subsets of results.

¹ See OVER clause for OLAP window expressions

² See LAG and LEAD functions

³ See RANK function

⁴ See DENSE_RANK function

⁵ See PERCENT_RANK function

⁶ See CUME_DIST function

⁷ See NTILE function