Difference between revisions of "Portable SQL/Common/DBMS Differences"
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! Firebird | ! Firebird | ||
| − | | 31 || L,D || upper || case preserved with double quotes (") | + | | 31 || L,D (?) || upper || case preserved with double quotes (") |
|- | |- | ||
! MySQL | ! MySQL | ||
| Line 65: | Line 65: | ||
| 131 || L,NL,D,_,$,@,# || preserved || max. DB and Cursor name length is 28 | | 131 || L,NL,D,_,$,@,# || preserved || max. DB and Cursor name length is 28 | ||
|} | |} | ||
| + | |||
| + | Explanation of allowed symbols: | ||
| + | * L = Letters | ||
| + | * NL = Non-latin letters | ||
| + | * D = Digits | ||
In general, all identifiers must start with a letter or non-latin letter; digits and other symbols as first characters are often not allowed or change their meaning. | In general, all identifiers must start with a letter or non-latin letter; digits and other symbols as first characters are often not allowed or change their meaning. | ||
Since OpenDBX 1.1.4 the use of double quotes (") for identifiers (table and column names) is suggested. This complies to ANSI standards and is the only way to use reserved words and prevent clashes in the future if language constructs are extended by the database vendors. | Since OpenDBX 1.1.4 the use of double quotes (") for identifiers (table and column names) is suggested. This complies to ANSI standards and is the only way to use reserved words and prevent clashes in the future if language constructs are extended by the database vendors. | ||
Revision as of 16:16, 3 September 2006
Differences between implementations
NULL in column definition
This table is originally from "Building Truly Portable Database Applications in PHP": NULL
| Database | Default value | Definition allowed | Notes |
|---|---|---|---|
| Firebird | NULL | no | |
| MySQL | NULL | yes | |
| Oracle | NULL | yes | Empty strings considered NULL |
| PostgreSQL | NULL | yes | |
| SQL Server | NOT NULL | yes | |
| SQLite | NULL | yes | |
| Sybase ASE | NOT NULL | yes |
The "Definition allowed" column indicates if specifying NULL in table column definitions is allowed for CREATE TABLE statements - NOT NULL is always allowed. If "yes", the following statement doesn't generate an error:
CREATE TABLE mytable ( id INTEGER NULL )
Identifiers
Parts of this table are originally from "Building Truly Portable Database Applications in PHP": Column Name Case
| Database | Length | Allowed | Case | Notes |
|---|---|---|---|---|
| Firebird | 31 | L,D (?) | upper | case preserved with double quotes (") |
| MySQL | 63 | L,NL,D,_,$ | preserved | |
| Oracle | 30 | L,NL,D,_,$,# | upper | Info, max. DB name length is 8 |
| PostgreSQL | 63 | L,NL,D,_,$ | lower | case preserved with double quotes (") |
| SQL Server | 127 | L,NL,D,_,$,@,# | preserved | Info |
| SQLite | 255 | L,NL,D,_ | preserved | |
| Sybase ASE | 131 | L,NL,D,_,$,@,# | preserved | max. DB and Cursor name length is 28 |
Explanation of allowed symbols:
- L = Letters
- NL = Non-latin letters
- D = Digits
In general, all identifiers must start with a letter or non-latin letter; digits and other symbols as first characters are often not allowed or change their meaning.
Since OpenDBX 1.1.4 the use of double quotes (") for identifiers (table and column names) is suggested. This complies to ANSI standards and is the only way to use reserved words and prevent clashes in the future if language constructs are extended by the database vendors.
