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Informix - Identifiers
This article describes identifiers in Informix Dynamic Server.
Identifier Rules
| Informix - Identifier Rules | |
|---|---|
| First Character | An alphabetical character and underscore (_) |
| Subsequent Characters | Alphanumeric characters, underscore (_) and dollar sign ($) |
| Maximum Length | 128 characters |
| Case Sensitivity | Identifiers are case insensitive |
| Standards | ANSI SQL |
Identifiers - Differences between Informix and other Databases
| Database | Identifiers | First Character | Subsequent Characters | Max Length |
|---|---|---|---|---|
| Oracle | Oracle Identifiers | Not allowed: _ | Allowed: # | 30 |
| SQL Server | SQL Server Identifiers | Allowed: @ and # | Allowed: @ and # | 128 |
| IBM DB2 | IBM DB2 Identifiers | Not allowed: _ | Not allowed: $ | 128 |
| MySQL | MySQL Identifiers | Allowed: digit Not allowed: _ | No differences | 64 |
| PostgreSQL | PostgreSQL Identifiers | No differences | No differences | 63 |
| Sybase ASE | Sybase ASE Identifiers | Allowed: @ and # | Allowed: @ and # | 255 |
| Sybase ASA | Sybase ASA Identifiers | Allowed: $, @ and # | Allowed: @ and # | 128 |
| Teradata | Teradata Identifiers | Allowed: $ and # | Allowed: # | 30 |
| HP Neoview | HP Neoview Identifiers | Not allowed: _ | Not allowed: $ | 128 |
| Interbase/Firebird | Interbase/Firebird Identifiers | Not allowed: _ | No differences | 67 |
Quoted or Delimited Identifiers
| Informix - Quoted Identifiers | |
|---|---|
| Quotation Marks | Double quotation marks (“”), can't be specified for the database name |
| Characters | Any including quotes |
| Maximum Length | 128 characters, not including the quotation marks |
| Case Sensitivity | Case sensitive. For example, “tab 1” and “Tab 1” are considered as different |
| Notes | When DELIMIDENT environment variable is set, Informix follows the SQL-92 rules for the use of double quotation marks (“) and the single quotation mark (') in SQL statements. |
Quoted Identifiers - Differences between Informix and other Databases
| Database | Identifiers | Quotation Marks | Characters | Case Sensitivity |
|---|---|---|---|---|
| Oracle | Oracle Quoted Identifiers | ”“ | Any except quotes | Case sensitive |
| SQL Server | SQL Server Quoted Identifiers | [] and ”“ | Any except quotes | Case insensitive |
| IBM DB2 | IBM DB2 Quoted Identifiers | ”“ | Any including quotes | Case sensitive |
| MySQL | MySQL Quoted Identifiers | `` and ”“ | Any except quotes | Case sensitive |
| PostgreSQL | PostgreSQL Quoted Identifiers | ”“ | Any including quotes | Case sensitive |
| Sybase ASE | Sybase ASE Quoted Identifiers | [] and ”“ | Any except pound sign (#) as the first character | Case insensitive |
| Sybase ASA | Sybase ASA Quoted Identifiers | [] and ”“ | Any | Case insensitive |
| Teradata | Teradata Quoted Identifiers | ”“ | Any including quotes | Case insensitive |
| HP Neoview | HP Neoview Quoted Identifiers | ”“ | Any except at sign (@), forward slash (/), circumflex character (^) as the first character and space(s) as the last character(s) | Case sensitive |
| Interbase/Firebird | Interbase/Firebird Quoted Identifiers | ”“ | Any character except space(s) as the last character(s) | Case sensitive |