database guidelines #71
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This is the collection of guidelines for database work. futher information can be found here owncloud-archive/documentation#3805
PVince81
reviewed
Sep 11, 2018
| ** When using a condition based on empty strings, use `is not null` with Oracle instead | ||
| ** Oracle can only compare the first 4000 bytes of a `CLOB` column | ||
| ** Make sure to properly escape column names when using custom functions with `createFunction`. the escaping is usually done automatically by the query builder otherwise. Oracle is the most likely to complain about unquoted columns while other databases will work fine | ||
| * Always add the table name when calling `lastInsertId($tableName)`, it is required by Oracle to return correct values |
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add a second "*" as this belongs to the Oracle block
| * Oracle compatibility specifics: | ||
| ** For Oracle `null` and empty strings are the same thing. Need special handling to catch these cases | ||
| ** When reading values, make sure to convert null to empty string when expected | ||
| ** Keep this in mind when designing DB schema and values expectations. |
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I think you can remove this line
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Alternatively, it could be added as a lead-in sentence above the list.
settermjd
reviewed
Sep 12, 2018
| ** Oracle can only compare the first 4000 bytes of a `CLOB` column | ||
| ** Make sure to properly escape column names when using custom functions with `createFunction`. the escaping is usually done automatically by the query builder otherwise. Oracle is the most likely to complain about unquoted columns while other databases will work fine | ||
| * Always add the table name when calling `lastInsertId($tableName)`, it is required by Oracle to return correct values | ||
| * In general don't specify a value for autoincrement column. if you have to, keep in mind that Oracle's autoincrement trigger will get in the way on `INSERT`, so you'll need a subsequent `UPDATE` to properly adjust the value |
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I'd rewrite this as:
In general, don't specify a value for an autoincrement column. If you have to, keep in mind that Oracle's autoincrement trigger will get in the way on INSERT. As a result, you'll need a subsequent UPDATE to properly adjust the value.
settermjd
reviewed
Sep 12, 2018
| ** Make sure to properly escape column names when using custom functions with `createFunction`. the escaping is usually done automatically by the query builder otherwise. Oracle is the most likely to complain about unquoted columns while other databases will work fine | ||
| * Always add the table name when calling `lastInsertId($tableName)`, it is required by Oracle to return correct values | ||
| * In general don't specify a value for autoincrement column. if you have to, keep in mind that Oracle's autoincrement trigger will get in the way on `INSERT`, so you'll need a subsequent `UPDATE` to properly adjust the value | ||
| * *Always* make sure there are unit tests for the database operations with queries to verify the result, this will help find out whether the database related code works on all databases and often times might reveal database quirks |
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Break this sentence into two, with the second sentence starting at "this will". It makes it easier to read and digest.
settermjd
reviewed
Sep 12, 2018
| * *Always* make sure there are unit tests for the database operations with queries to verify the result, this will help find out whether the database related code works on all databases and often times might reveal database quirks | ||
| * Running unit tests with specific databases: `make test-php TEST_PHP_SUITE=path/to/test/file.php TEST_DATABASE=$databasetype` where "$databasetype" is one of "sqlite", "mysql", "mariadb", "pgsql", "oci" and "mysqlmb4" | ||
| * String concatenation should be done like this: | ||
| ** `CONCAT(str1, str2, ... strN)` for Mysql |
settermjd
reviewed
Sep 12, 2018
| * Running unit tests with specific databases: `make test-php TEST_PHP_SUITE=path/to/test/file.php TEST_DATABASE=$databasetype` where "$databasetype" is one of "sqlite", "mysql", "mariadb", "pgsql", "oci" and "mysqlmb4" | ||
| * String concatenation should be done like this: | ||
| ** `CONCAT(str1, str2, ... strN)` for Mysql | ||
| ** `str1 || str1 ... || strN` Sqlite/PgSQL/Oracle |
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s/Sqlite/SQLite/g
s/PgSQL/pgSQL/g
settermjd
reviewed
Sep 12, 2018
| * Don't add more than 999 conditions in a `WHERE ... IN ...` statement but chunk it into separate queries when using SQLite | ||
| * When processing big tables, always do this in chunks, don't store the whole table in memory | ||
| * Oracle compatibility specifics: | ||
| ** For Oracle `null` and empty strings are the same thing. Need special handling to catch these cases |
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s/For Oracle/For Oracle,/g
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s/Need special handling/Special handling is required/g
settermjd
reviewed
Sep 12, 2018
| * When processing big tables, always do this in chunks, don't store the whole table in memory | ||
| * Oracle compatibility specifics: | ||
| ** For Oracle `null` and empty strings are the same thing. Need special handling to catch these cases | ||
| ** When reading values, make sure to convert null to empty string when expected |
There was a problem hiding this comment.
s/convert null to empty string/convert nulls to empty strings/g
settermjd
reviewed
Sep 12, 2018
| ** Keep this in mind when designing DB schema and values expectations. | ||
| ** When using a condition based on empty strings, use `is not null` with Oracle instead | ||
| ** Oracle can only compare the first 4000 bytes of a `CLOB` column | ||
| ** Make sure to properly escape column names when using custom functions with `createFunction`. the escaping is usually done automatically by the query builder otherwise. Oracle is the most likely to complain about unquoted columns while other databases will work fine |
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s/the escaping/The escaping/g
"otherwise", at the end of the second sentence seems superfluous.
settermjd
suggested changes
Sep 12, 2018
settermjd
added
enhancement
|
@voroyam, thanks for making the final changes. |
settermjd
approved these changes
Sep 13, 2018
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This is the collection of guidelines for database work.
futher information can be found here
owncloud-archive/documentation#3805