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Overview
| Comment: | Update to the virtual table documentation - in particular the documentation on the xUpdate method. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
feccb40483d9b5550015462ac07d88e2 |
| User & Date: | drh 2009-04-14 18:15:09.000 |
Context
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2009-04-14
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| 18:20 | More virtual table documentation tweaks. (check-in: 0d0a959a73 user: drh tags: trunk) | |
| 18:15 | Update to the virtual table documentation - in particular the documentation on the xUpdate method. (check-in: feccb40483 user: drh tags: trunk) | |
| 11:45 | Additional virtual table documentation improvements. Fix the "when-to-use" document to omit discussion of the obsolete bitmap size limits. (check-in: 9ef2178fee user: drh tags: trunk) | |
Changes
Changes to pages/vtab.in.
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871 872 873 874 875 876 877 | ); </pre></blockquote> <p>All changes to a virtual table are made using the xUpdate method. This one method can be used to insert, delete, or update. <p>The argc parameter specifies the number of entries in the argv array. | | | > > > | | | | | > > > | | | | > > | | | | 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 |
);
</pre></blockquote>
<p>All changes to a virtual table are made using the xUpdate method.
This one method can be used to insert, delete, or update.
<p>The argc parameter specifies the number of entries in the argv array.
Every argv entry will have a non-NULL value in C but may contain the
SQL value NULL. In other words, it is always true that
<tt>argv[i]!=0</tt> for <b>i</b> between 0 and <tt>argc-1</tt>.
However, it might be the case that
<tt>sqlite3_value_type(argv[i])==SQLITE_NULL</tt>.
<p>The argv[0] parameter is the [rowid] of a row in the virtual table
to be deleted. If argv[0] is an SQL NULL, then no deletion occurs.
<p>The argv[1] parameter is the rowid of a new row to be inserted
into the virtual table. If argv[1] is an SQL NULL, then the implementation
must choose a rowid for the newly inserted row. Subsequent argv[]
entries contain values of the columns of the virtual table, in the
order that the columns were declared. The number of columns will
match the table declaration that the [xConnect] or [xCreate] method made
using the [sqlite3_declare_vtab()] call. All hidden columns are included.
<p>When doing an insert without a rowid (argc>1, argv[1] is an SQL NULL), the
implementation must set *pRowid to the rowid of the newly inserted row;
this will become the value returned by the [sqlite3_last_insert_rowid()]
function. Setting this value in all the other cases is a harmless no-op;
the SQLite engine ignores the *pRowid return value if argc==1 or
argv[1] is not an SQL NULL.
<p>Each call to xUpdate will fall into one of cases shown below.
Not that references to <b>argv[i]</b> mean the SQL value
held within the argv[i] object, not the argv[i]
object itself.
<blockquote>
<dl>
<dt><b>argc = 1</b>
<dd><p>The single row with rowid equal to argv[0] is deleted. No insert occurs.
<dt><b>argc > 1 <br> argv[0] = NULL</b>
<dd><p>A new row is inserted with a rowid argv[1] and column values in
argv[2] and following. If argv[1] is an SQL NULL,
the a new unique rowid is generated automatically.
<dt><b>argc > 1 <br> argv[0] ≠ NULL <br> argv[0] = argv[1]</b>
<dd><p>The row with rowid argv[0] is updated with new values
in argv[2] and following parameters.
<dt><b>argc > 1 <br> argv[0] ≠ NULL <br> argv[0] ≠ argv[1]</b>
<dd><p> The row with rowid argv[0] is updated with rowid argv[1]
and new values in argv[2] and following parameters. This will occur
when an SQL statement updates a rowid, as in the statement:
<blockquote>
[UPDATE] table SET rowid=rowid+1 WHERE ...;
</blockquote>
</dl>
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