CONNX Data Integration Suite 14.7.0 | Reference Guide | SQL Grammar | SQL Language Elements | SQL Tokens, Identifiers, Delimiters
 
SQL Tokens, Identifiers, Delimiters
SQL Tokens
SQL consists of lexical units called tokens. Tokens consist of identifiers, constants and keywords. Delimiters are used to separate tokens.
Identifiers
Identifiers are used to identify or name objects like tables, columns, schemas, and indexes. There are two kinds of identifiers - regular and delimited. CONNX can handle identifiers of up to 128 characters.
Regular identifiers are:
*Not delimited by double quotes
*Case insensitive
*Comprised of only letters, digits and the underscore character
Delimited identifiers are:
*Delimited by double quotes
*Case sensitive
*Comprised of letters, digits, and any of the following characters: % & ' ( ) * + , - . / : ; < = > ? [ ]
Use a delimited identifier if your object:
*Contain blanks
*Does not start with a letter
*Is identical to a keyword
*Is case-sensitive
*Contains any of the following characters: % & ' ( ) * + , - . / : ; < = > ? [ ]
Examples:
Incorrect Indetifier
Correct Identifier
Explanation
create view table as select
TABLE_NAME,TABLE_TYPE
from information_schema.tables
where table_schema=USER;
create view "table" as select
TABLE_NAME,TABLE_TYPE
from information_schema.tables
where table_schema=USER;
Table is a keyword and can not be used as a regular identifier. If it is used as a delimited identifier, it can specify a view name.
select col1-1 from tab1;
select "col1-1" from tab1;
col1-1 is a numeric operation in select list and can not be used as a regular identifier. If it is used as a delimited identifier, it can specify a column name.
Delimiters
A delimiter is used to separate the lexical units in the language for compiler processing. Delimiters are either spaces, control characters, comments, or special tokens. A comment must be preceded by two hyphens (--).
The following symbols are used as special tokens in SQL:
,
()
<
>
.
:
=
+
-
*
<>
<=
>=
/
;
?
~>
~<
~=
"
||