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Overview
| Comment: | Fix typos in the partial index document. |
|---|---|
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 8bf9d71fd6597a013d7f25a4738362ff |
| User & Date: | drh 2013-08-08 02:54:33 |
Context
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2013-08-08
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| 17:58 | Fix typos in the "vfs.html" document. check-in: 37c89b86f8 user: drh tags: trunk | |
| 02:54 | Fix typos in the partial index document. check-in: 8bf9d71fd6 user: drh tags: trunk | |
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2013-08-07
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| 23:38 | Add documentation for SQLITE_ALLOW_URI_AUTHORITY. check-in: cadb86b398 user: drh tags: trunk | |
Changes
Changes to pages/partialindex.in.
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</p> <p> ^The expression following the WHERE clause may contain operators, literal values, and names of columns in the table being indexed. ^The WHERE clause may <em>not</em> contains subqueries, references to other tables, functions, or [bound parameters]. The LIKE, GLOB, MATCH, and REGEXP operators in SQLite as functions by the same name. ^Since functions are prohibited in the WHERE clause of a CREATE INDEX statement, so too are the LIKE, GLOB, MATCH, and REGEXP operators.</p> <p> ^Only rows of the table for which the WHERE clause evaluates to true are included in the index. ^If the WHERE clause expression evaluates to NULL or to false for some row of the table, then those rows are omitted from the index. </p> <p> ^The columns referenced in the WHERE clause of a partial index can be any of the columns in the table, not just columns that happen to be indexed. However, it is very common for the WHERE clause ................................................................................ team_id INTEGER REFERENCES team, is_team_leader BOOLEAN, -- other fields elided ); </pre></blockquote>)^ <p>The team_id field cannot be unique because there usually multiple people on the same time. One cannot make the combination of team_id and is_team_leader unique since there are usually multiple non-leaders on each team. ^(The solution to enforcing one leader per team is to create a unique index on team_id but restricted to those entries for which is_team_leader is true:</p> <blockquote> CREATE UNIQUE INDEX team_leader ON person(team_id) WHERE is_team_leader; </blockquote>)^ ^(<p>Coincidentally, that same index is useful for locating the team leader of a particular time:</p> <blockquote> SELECT person_id FROM person WHERE is_team_leader AND team_id=?1; </blockquote>)^ <h2>3.0 Queries Using Partial Indexes</h2> |
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</p> <p> ^The expression following the WHERE clause may contain operators, literal values, and names of columns in the table being indexed. ^The WHERE clause may <em>not</em> contains subqueries, references to other tables, functions, or [bound parameters]. The LIKE, GLOB, MATCH, and REGEXP operators in SQLite are implemented as functions by the same name. ^Since functions are prohibited in the WHERE clause of a CREATE INDEX statement, so too are the LIKE, GLOB, MATCH, and REGEXP operators.</p> <p> ^Only rows of the table for which the WHERE clause evaluates to true are included in the index. ^If the WHERE clause expression evaluates to NULL or to false for some rows of the table, then those rows are omitted from the index. </p> <p> ^The columns referenced in the WHERE clause of a partial index can be any of the columns in the table, not just columns that happen to be indexed. However, it is very common for the WHERE clause ................................................................................ team_id INTEGER REFERENCES team, is_team_leader BOOLEAN, -- other fields elided ); </pre></blockquote>)^ <p>The team_id field cannot be unique because there usually multiple people on the same team. One cannot make the combination of team_id and is_team_leader unique since there are usually multiple non-leaders on each team. ^(The solution to enforcing one leader per team is to create a unique index on team_id but restricted to those entries for which is_team_leader is true:</p> <blockquote> CREATE UNIQUE INDEX team_leader ON person(team_id) WHERE is_team_leader; </blockquote>)^ ^(<p>Coincidentally, that same index is useful for locating the team leader of a particular team:</p> <blockquote> SELECT person_id FROM person WHERE is_team_leader AND team_id=?1; </blockquote>)^ <h2>3.0 Queries Using Partial Indexes</h2> |