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<!-- keywords: sqlite3_keyword_check sqlite3_keyword_count sqlite3_keyword_name -->
<div class=nosearch>
<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
<h2>SQL Keyword Checking</h2>
</div>
<blockquote><pre>
int sqlite3_keyword_count(void);
int sqlite3_keyword_name(int,const char**,int*);
int sqlite3_keyword_check(const char*,int);
</pre></blockquote>
<p>
These routines provide access to the set of SQL language keywords
recognized by SQLite. Applications can uses these routines to determine
whether or not a specific identifier needs to be escaped (for example,
by enclosing in double-quotes) so as not to confuse the parser.</p>
<p>The sqlite3_keyword_count() interface returns the number of distinct
keywords understood by SQLite.</p>
<p>The sqlite3_keyword_name(N,Z,L) interface finds the N-th keyword and
makes *Z point to that keyword expressed as UTF8 and writes the number
of bytes in the keyword into *L. The string that *Z points to is not
zero-terminated. The sqlite3_keyword_name(N,Z,L) routine returns
SQLITE_OK if N is within bounds and SQLITE_ERROR if not. If either Z
or L are NULL or invalid pointers then calls to
sqlite3_keyword_name(N,Z,L) result in undefined behavior.</p>
<p>The sqlite3_keyword_check(Z,L) interface checks to see whether or not
the L-byte UTF8 identifier that Z points to is a keyword, returning non-zero
if it is and zero if not.</p>
<p>The parser used by SQLite is forgiving. It is often possible to use
a keyword as an identifier as long as such use does not result in a
parsing ambiguity. For example, the statement
"CREATE TABLE BEGIN(REPLACE,PRAGMA,END);" is accepted by SQLite, and
creates a new table named "BEGIN" with three columns named
"REPLACE", "PRAGMA", and "END". Nevertheless, best practice is to avoid
using keywords as identifiers. Common techniques used to avoid keyword
name collisions include:
<ul>
<li> Put all identifier names inside double-quotes. This is the official
SQL way to escape identifier names.
<li> Put identifier names inside [...]. This is not standard SQL,
but it is what SQL Server does and so lots of programmers use this
technique.
<li> Begin every identifier with the letter "Z" as no SQL keywords start
with "Z".
<li> Include a digit somewhere in every identifier name.
</ul></p>
<p>Note that the number of keywords understood by SQLite can depend on
compile-time options. For example, "VACUUM" is not a keyword if
SQLite is compiled with the <a href="../compile.html#omit_vacuum">-DSQLITE_OMIT_VACUUM</a> option. Also,
new keywords may be added to future releases of SQLite.
</p><p>See also lists of
<a href="../c3ref/objlist.html">Objects</a>,
<a href="../c3ref/constlist.html">Constants</a>, and
<a href="../c3ref/funclist.html">Functions</a>.</p>
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