SQL acceptable by 4D
(No version information available, might only be in Git)
SQL acceptable by 4D — PDO and SQL 4D
Description
4D implements strictly the ANSI 89 standard, and have it enforced. It is highly recommended to read the 4D SQL documentation to learn about the available commands. The URL of the manual is: » http://doc.4d.com/. Below is a list of 4D SQL characteristics: it is not exhaustive, but may serve as an introduction.
| Characteristics | Alternative | Note |
|---|---|---|
| INTEGER | Modify the SQL to use INT. | INT is the supported integer type in 4Dv12.0. |
| CHAR | Use VARCHAR instead. | Unsupported in 4Dv12.0 |
| UNION | Unsupported. Make separate queries. | Unsupported in 4Dv12.0 |
| SELECT 1 + 1; | SELECT 1 + 1 FROM _USER_SCHEMAS; | FROM is required |
| FLOAT | Cast the FLOAT value into a FLOAT or STRING, with an SQL 4D function (CAST, ROUND, TRUNC or TRUNCATE) | Unsupported in current versions of the PDO_4D driver |
| Strong typing | Take care your SQL query, or your PHP code provides data with the expected type | One must provide the right type that 4D expect. One can't insert '1' (as a string) in an INTEGER column. |
| PDO::execute($row)() : only works if all the table's column are of type TEXT or VARCHAR | Use the prepared statements, and use the right types. | The PDO extension cast all values through execute() as string, and expect the SQL database to parse the values. |
| SELECT NULL FROM TABLE | Do not use NULL constants. Extract them from the table | It is not allowed to use the NULL constant in the select list |
| SELECT * FROM TABLE WHERE 1 | Use WHERE 1 = 1 | A constant can't be used in a WHERE clause |
| SHOW TABLES | Use system tables | The list of tables, schemas, index, etc. are in these system tables : _USER_TABLES, _USER_COLUMNS, _USER_INDEXES, _USER_CONSTRAINTS, _USER_IND_COLUMNS, _USER_CONS_COLUMNS, and _USER_SCHEMAS. |
| SQL structure delimiter | Use the following function to protect SQL elements: function sqlEscapeElement(elem) { return '[' . str_replace(']',']]', $elem) . ']'; } | To escape SQL elements names (tables, fields, users, groups, schema, primary key, etc.), the whole identifier must be between square brackets, and the closing brackets ']' must be doubled. |
English translation
You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.
Thank you in advance.
Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-ref.pdo-4d.sql4d.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.
