<i>Informix Guide to SQL: Syntax</i>

Informix Guide to SQL: Syntax
Introduction

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Documentation Conventions

This section describes the conventions that this manual uses. These conventions make it easier to gather information from this and other Informix manuals.

The following conventions are covered:

Typographical conventions
Icon conventions
Syntax conventions
Sample-code conventions

Typographical Conventions

This manual uses the following standard set of conventions to introduce new terms, illustrate screen displays, describe command syntax, and so forth.

(1 of 2)
Convention	Meaning
`KEYWORD`	All keywords appear in uppercase letters in a serif font.
italics	Within text, new terms and emphasized words appear in italics. Within syntax diagrams, values that you are to specify appear in italics.
boldface	`I`dentifiers (names of classes, objects, constants, events, functions, program variables, forms, labels, and reports), environment variables, database names, filenames, table names, column names, icons, menu items, command names, and other similar terms appear in boldface.
`monospace`	Information that the product displays and information that you enter appear in a monospace typeface.
`KEYSTROKE`	Keys that you are to press appear in uppercase letters in a sans serif font.
	This symbol indicates the end of feature-, product-, platform-, or compliance-specific information.

Tip: When you are instructed to "enter" characters or to "execute" a command, immediately press RETURN after the entry. When you are instructed to "type" the text or to "press" other keys, no RETURN is required.

Icon Conventions

Throughout the documentation, you will find text that is identified by several different types of icons. This section describes these icons.

Comment Icons

Comment icons identify warnings, important notes, or tips. This information is always displayed in italics.


Icon	Description
	The warning icon identifies vital instructions, cautions, or critical information.
	The important icon identifies significant information about the feature or operation that is being described.
	The tip icon identifies additional details or shortcuts for the functionality that is being described.

Feature and Product Icons

Feature and product icons identify paragraphs that contain feature-specific or product-specific information.


Icon	Description
	Identifies information that relates to the Informix Global Language Support (`GLS)` feature.
	Identifies information that is valid only for `DB-A`ccess.
	Identifies information that is valid only for `SQL` statements in `INFORMIX-ESQL/C`.
	Identifies information that is valid only for `INFORMIX-ESQL/C.`
	Identifies information that is valid only for `INFORMIX-O`nLine/`O`ptical.
	Identifies information that is valid only if you are using Informix Stored Procedure Language (`SPL`).

These icons can apply to a row in a table, one or more paragraphs, or an entire section. A symbol indicates the end of the feature- or product-specific information.

Compliance Icons

Compliance icons indicate paragraphs that provide guidelines for complying with a standard.


Icon	Description
	Identifies information that is specific to an `ANSI`-compliant database.
	Identifies functionality that conforms to `X/O`pen. This functionality is available when you compile your `SQL` `API` with the -xopen flag.

These icons can apply to a row in a table, one or more paragraphs, or an entire section. A symbol indicates the end of the compliance information.

Syntax Conventions

This section describes conventions for syntax diagrams. Each diagram displays the sequences of required and optional keywords, terms, and symbols that are valid in a given statement or segment, as Figure 1 shows.

Figure 1
Example of a Simple Syntax Diagram

Each syntax diagram begins at the upper-left corner and ends at the upper-right corner with a vertical terminator. Between these points, any path that does not stop or reverse direction describes a possible form of the statement.

Syntax elements in a path represent terms, keywords, symbols, and segments that can appear in your statement. The path always approaches elements from the left and continues to the right, except in the case of separators in loops. For separators in loops, the path approaches counterclockwise from the right. Unless otherwise noted, at least one blank character separates syntax elements.

Elements That Can Appear on the Path

You might encounter one or more of the following elements on a path.

(1 of 3)
Element	Description
`KEYWORD`	A word in `UPPERCASE` letters is a keyword. You must spell the word exactly as shown; however, you can use either uppercase or lowercase letters.
( . , ; @ + * - / )	Punctuation and other nonalphanumeric characters are literal symbols that you must enter exactly as shown.
`' '`	Single quotes are literal symbols that you must enter as shown.
variable	A word in italics represents a value that you must supply. A table immediately following the diagram explains the value.
	A reference in a box represents a subdiagram. Imagine that the subdiagram is spliced into the main diagram at this point. When a page number is not specified, the subdiagram appears on the same page.
	An icon is a warning that this path is valid only for some products, or only under certain conditions. Characters on the icons indicate what products or conditions support the path.
	These icons might appear in a syntax diagram:
		This path is valid only for `DB-A`ccess.
		This path is valid only for `INFORMIX-ESQL/C`.
		This path is valid for external routines.
		This path is valid only if you are using Informix Stored Procedure Language (`SPL`).
		This path is valid for the `SQL` Editor.
		This path is valid only for `INFORMIX`-`O`n`L`ine/`O`ptical.
		This path is an Informix extension to `ANSI` `SQL`-92 entry-level standard `SQL`. If you initiate Informix extension checking and include this syntax branch, you receive a warning. If you have set the `DBANSIWARN` environment variable at compile time, or have used the -ansi compile flag, you receive warnings at compile time. If you have `DBANSIWARN` set at runtime, or if you compiled with the -ansi flag, warning flags are set in the sqlwarn structure.
		This path is valid only if your database or application uses a nondefault `GLS` locale.
	A shaded option is the default action.
	Syntax that is enclosed between a pair of arrows is a subdiagram.
	The vertical line terminates the syntax diagram.
	A branch below the main path indicates an optional path. (Any term on the main path is required, unless a branch can circumvent it.)
	A set of multiple branches indicates that a choice among more than two different paths is available.
	A loop indicates a path that you can repeat. Punctuation along the top of the loop indicates the separator symbol for list items. If no symbol appears, a blank space is the separator.
	A gate ( ) on a path indicates that you can only use that path the indicated number of times, even if it is part of a larger loop. Here you can specify size no more than three times.

How to Read a Syntax Diagram

Figure 2 shows a syntax diagram that uses many of the elements that are listed in the previous table.


Figure 2 Example of a Syntax Diagram

The three icons at the top left of this diagram indicate that you can construct this statement if you are using DB-Access, ESQL/C, or the SQL Editor. To use the diagram to construct a statement, begin at the far left with the keywords DELETE FROM. Then follow the diagram to the right, proceeding through the options that you want.

To construct a DELETE statement

1. You must type the words DELETE FROM.

2. If you are using DB-Access, ESQL/C, or the SQL Editor, you can delete a table, view, or synonym:

Follow the diagram by typing the table name, view name, or synonym, as desired. Refer to the appropriate segment for available syntax options.
You must type the keyword WHERE.
If you are using DB-Access or the SQL Editor, you must include the Condition clause to specify a condition to delete. To find the syntax for deleting a condition, go to the "Condition" segment on page 1-803.
If you are using ESQL/C or SPL, you can include either the Condition clause to delete a specific condition or the CURRENT OF cursorname clause to delete a row from the table.

3. If you are using ESQL/C, you can also choose to delete from a collection-derived table:

Follow the diagram by going to the segment "Collection Derived Table" on page 1-800. Follow the syntax for the segment.
You can stop, taking the direct route to the terminator, or you can include the WHERE CURRENT OF cursorname clause to delete a row from a collection-derived table.

4. Follow the diagram to the terminator. Your DELETE statement is complete.

Sample-Code Conventions

Examples of SQL code occur throughout this manual. Except where noted, the code is not specific to any single Informix application development tool. If only SQL statements are listed in the example, they are not delimited by semicolons. For instance, you might see the code in the following example:

CONNECT TO stores7

...



DELETE FROM customer

	WHERE customer_num = 121

...



COMMIT WORK

DISCONNECT CURRENT

To use this SQL code for a specific product, you must apply the syntax rules for that product. For example, if you are using the Query-language option of DB-Access, you must delimit multiple statements with semicolons. If you are using an SQL API, you must use EXEC SQL at the start of each statement and a semicolon (or other appropriate delimiter) at the end of the statement.

Tip: Ellipsis points in a code example indicate that more code would be added in a full application, but it is not necessary to show it to describe the concept being discussed.

For detailed directions on using SQL statements for a particular application development tool or SQL API, see the manual for your product.

Informix Guide to SQL: SyntaxIntroduction Home Contents Index Master Index New Book

Documentation Conventions

Typographical Conventions

Sample-Code Conventions

Informix Guide to SQL: Syntax
Introduction

Home Contents Index Master Index New Book