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<h1 align="center">SQL As Understood By SQLite</h1><p><a href="lang.html">[Top]</a></p><h2>Core Functions</h2>
<p>The core functions shown below are available by default.
<a href="lang_datefunc.html">Date & Time functions</a> and
<a href="lang_aggfunc.html">aggregate functions</a> are documented separately. An
application may define additional
functions written in C and added to the database engine using
the <a href="c3ref/create_function.html">sqlite3_create_function()</a> API.</p>
<table border=0 cellpadding=10>
<tr><td valign="top" align="right" width="120"><a name="abs"></a>
abs(<i>X</i>)</td><td valign="top">
The abs(X) function returns the absolute value of the numeric
argument X. Abs(X) returns NULL if X is NULL.
Abs(X) return 0.0 if X is a string or blob
that cannot be converted to a numeric value. If X is the
integer -9223372036854775807 then abs(X) throws an integer overflow
error since there is no equivalent positive 64-bit two complement value.
</td></tr><tr><td valign="top" align="right" width="120"><a name="changes"></a>
changes()</td><td valign="top">
The changes() function returns the number of database rows that were changed
or inserted or deleted by the most recently completed INSERT, DELETE,
or UPDATE statement, exclusive of statements in lower-level triggers.
The changes() SQL function is a wrapper around the <a href="c3ref/changes.html">sqlite3_changes()</a>
C/C++ function and hence follows the same rules for counting changes.
</td></tr><tr><td valign="top" align="right" width="120"><a name="coalesce"></a>
coalesce(<i>X</i>,<i>Y</i>,...)</td><td valign="top">
The coalesce() function returns a copy of its first non-NULL argument, or
NULL if all arguments are NULL. Coalesce() must be at least
2 arguments.
</td></tr><tr><td valign="top" align="right" width="120"><a name="glob"></a>
glob(<i>X</i>,<i>Y</i>)</td><td valign="top">
The glob(X,Y) function is equivalent to the
expression "<b>Y GLOB X</b>".
Note that the X and Y arguments are reversed in the glob() function
relative to the infix <a href="lang_expr.html#glob">GLOB</a> operator.
If the <a href="c3ref/create_function.html">sqlite3_create_function()</a> interface is used to
override the glob(X,Y) function with an alternative implementation then
the <a href="lang_expr.html#glob">GLOB</a> operator will invoke the alternative implementation.
</td></tr><tr><td valign="top" align="right" width="120"><a name="ifnull"></a>
ifnull(<i>X</i>,<i>Y</i>)</td><td valign="top">
The ifnull() function returns a copy of its first non-NULL argument, or
NULL if both arguments are NULL. Ifnull() must have exactly 2 arguments.
The ifnull() function is equivalent to <a href="lang_corefunc.html#coalesce">coalesce()</a> with two arguments.
</td></tr><tr><td valign="top" align="right" width="120"><a name="hex"></a>
hex(<i>X</i>)</td><td valign="top">
The hex() function interprets its argument as a BLOB and returns
a string which is the upper-case hexadecimal rendering of the content of
that blob.
</td></tr><tr><td valign="top" align="right" width="120"><a name="last_insert_rowid"></a>
last_insert_rowid()</td><td valign="top">
The last_insert_rowid() function returns the <a href="lang_createtable.html#rowid">ROWID</a>
of the last row insert from the database connection which invoked the
function.
The last_insert_rowid() SQL function is a wrapper around the
<a href="c3ref/last_insert_rowid.html">sqlite3_last_insert_rowid()</a> C/C++ interface function.
</td></tr><tr><td valign="top" align="right" width="120"><a name="length"></a>
length(<i>X</i>)</td><td valign="top">
For a string value X, the length(X) function returns the number of
characters (not bytes) in X prior to the first NUL character.
Since SQLite strings do not normally contain NUL characters, the length(X)
function will usually return the total number of characters in the string X.
For a blob value X, length(X) returns the number of bytes in the blob.
If X is NULL then length(X) is NULL.
If X is numeric then length(X) returns the length of a string
representation of X.
</td></tr><tr><td valign="top" align="right" width="120"><a name="like"></a>
like(<i>X</i>,<i>Y</i>)<br></br>like(<i>X</i>,<i>Y</i>,<i>Z</i>)</td><td valign="top">
The like() function is used to implement the
"<b>Y LIKE X [ESCAPE Z]</b>" expression.
If the optional ESCAPE clause is present, then the
like() function is invoked with three arguments. Otherwise, it is
invoked with two arguments only. Note that the X and Y parameters are
reversed in the like() function relative to the infix <a href="lang_expr.html#like">LIKE</a> operator.
The <a href="c3ref/create_function.html">sqlite3_create_function()</a> interface can be used to override the
like() function and thereby change the operation of the
<a href="lang_expr.html#like">LIKE</a> operator. When overriding the like() function, it may be important
to override both the two and three argument versions of the like()
function. Otherwise, different code may be called to implement the
<a href="lang_expr.html#like">LIKE</a> operator depending on whether or not an ESCAPE clause was
specified.
</td></tr><tr><td valign="top" align="right" width="120"><a name="load_extension"></a>
load_extension(<i>X</i>)<br></br>load_extension(<i>X</i>,<i>Y</i>)</td><td valign="top">
The load_extension(X,Y) function loads SQLite extensions out of the shared
library file named X using the entry point Y. The result of load_extension()
is always a NULL. If Y is omitted then the default entry point
of <b>sqlite3_extension_init</b> is used. The load_extension() function
raises an exception if the extension fails to load or initialize correctly.
<p>The load_extension() function will fail if the extension attempts to
modify or delete an SQL function or collating sequence. The
extension can add new functions or collating sequences, but cannot
modify or delete existing functions or collating sequences because
those functions and/or collating sequences might be used elsewhere
in the currently running SQL statement. To load an extension that
changes or deletes functions or collating sequences, use the
<a href="c3ref/load_extension.html">sqlite3_load_extension()</a> C-language API.</p>
</td></tr><tr><td valign="top" align="right" width="120"><a name="lower"></a>
lower(<i>X</i>)</td><td valign="top">
The lower(X) function returns a copy of string X with all ASCII characters
converted to lower case. The default built-in lower() function works
for ASCII characters only. To do case conversions on non-ASCII
characters, load the ICU extension.
</td></tr><tr><td valign="top" align="right" width="120"><a name="ltrim"></a>
ltrim(<i>X</i>)<br></br>ltrim(<i>X</i>,<i>Y</i>)</td><td valign="top">
The ltrim(X,Y) function returns a string formed by removing any and all
characters that appear in Y from the left side of X.
If the Y argument is omitted, ltrim(X) removes spaces from the left side
of X.
</td></tr><tr><td valign="top" align="right" width="120"><a name="maxoreunc"></a>
max(<i>X</i>,<i>Y</i>,...)</td><td valign="top">
The multi-argument max() function returns the argument with the
maximum value, or return NULL if any argument is NULL.
The multi-argument max() function searches its arguments from left to right
for an argument that defines a collating function and uses that collating
function for all string comparisons. If none of the arguments to max()
define a collating function, then the BINARY collating function is used.
Note that <b>max()</b> is a simple function when
it has 2 or more arguments but operates as an
<a href="lang_aggfunc.html#minggunc">aggregate function</a> if given only a single argument.
</td></tr><tr><td valign="top" align="right" width="120"><a name="minoreunc"></a>
min(<i>X</i>,<i>Y</i>,...)</td><td valign="top">
The multi-argument min() function returns the argument with the
minimum value.
The multi-argument min() function searches its arguments from left to right
for an argument that defines a collating function and uses that collating
function for all string comparisons. If none of the arguments to min()
define a collating function, then the BINARY collating function is used.
Note that <b>min()</b> is a simple function when
it has 2 or more arguments but operates as an
<a href="lang_aggfunc.html#maxggunc">aggregate function</a> if given
only a single argument.
</td></tr><tr><td valign="top" align="right" width="120"><a name="nullif"></a>
nullif(<i>X</i>,<i>Y</i>)</td><td valign="top">
The nullif(X,Y) function returns its first argument if the arguments are
different and NULL if the arguments are the same. The nullif(X,Y) function
searches its arguments from left to right for an argument that defines a
collating function and uses that collating function for all string
comparisons. If neither argument to nullif() defines a collating function
then the BINARY is used.
</td></tr><tr><td valign="top" align="right" width="120"><a name="quote"></a>
quote(<i>X</i>)</td><td valign="top">
The quote(X) function returns the text of an SQL literal which
is the value of its argument suitable for inclusion into an SQL statement.
Strings are surrounded by single-quotes with escapes on interior quotes
as needed. BLOBs are encoded as hexadecimal literals.
Strings with embedded NUL characters cannot be represented as string
literals in SQL and hence the returned string literal is truncated prior
to the first NUL.
</td></tr><tr><td valign="top" align="right" width="120"><a name="random"></a>
random()</td><td valign="top">
The random() function returns a pseudo-random integer
between -9223372036854775808 and +9223372036854775807.
</td></tr><tr><td valign="top" align="right" width="120"><a name="randomblob"></a>
randomblob(<i>N</i>)</td><td valign="top">
The randomblob(N) function return an N-byte blob containing pseudo-random
bytes. If N is less than 1 then a 1-byte random blob is returned.
<p>Hint: applications can generate globally unique identifiers
using this function together with <a href="lang_corefunc.html#hex">hex()</a> and/or
<a href="lang_corefunc.html#lower">lower()</a> like this:</p>
<blockquote>
hex(randomblob(16))<br></br>
lower(hex(randomblob(16)))
</blockquote>
</td></tr><tr><td valign="top" align="right" width="120"><a name="replace"></a>
replace(<i>X</i>,<i>Y</i>,<i>Z</i>)</td><td valign="top">
The replace(X,Y,Z) function returns a string formed by substituting
string Z for every occurrence of string Y in string X. The <a href="datatype3.html#collation">BINARY</a>
collating sequence is used for comparisons. If Y is an empty
string then return X unchanged. If Z is not initially
a string, it is cast to a UTF-8 string prior to processing.
</td></tr><tr><td valign="top" align="right" width="120"><a name="round"></a>
round(<i>X</i>)<br></br>round(<i>X</i>,<i>Y</i>)</td><td valign="top">
The round(X,Y) function returns a floating-point
value X rounded to Y digits to the right of the decimal point.
If the Y argument is omitted, it is assumed to be 0.
</td></tr><tr><td valign="top" align="right" width="120"><a name="rtrim"></a>
rtrim(<i>X</i>)<br></br>rtrim(<i>X</i>,<i>Y</i>)</td><td valign="top">
The rtrim(X,Y) function returns a string formed by removing any and all
characters that appear in Y from the right side of X.
If the Y argument is omitted, rtrim(X) removes spaces from the right
side of X.
</td></tr><tr><td valign="top" align="right" width="120"><a name="soundex"></a>
soundex(<i>X</i>)</td><td valign="top">
The soundex(X) function returns a string that is the soundex encoding
of the string X.
The string "?000" is returned if the argument is NULL or contains
no ASCII alphabetic characters.
This function is omitted from SQLite by default.
It is only available if the <a href="compile.html#soundex">SQLITE_SOUNDEX</a> compile-time option
is used when SQLite is built.
</td></tr><tr><td valign="top" align="right" width="120"><a name="sqlite_compileoption_get"></a>
sqlite_compileoption_get(<i>N</i>)</td><td valign="top">
The sqlite_compileoption_get() SQL function is a wrapper around the
<a href="c3ref/compileoption_get.html">sqlite3_compileoption_get()</a> C/C++ function.
This routine returns the N-th compile-time option used to build SQLite
or NULL if N is out of range. See also the <a href="pragma.html#pragma_compile_options">compile_options pragma</a>.
</td></tr><tr><td valign="top" align="right" width="120"><a name="sqlite_compileoption_used"></a>
sqlite_compileoption_used(<i>X</i>)</td><td valign="top">
The sqlite_compileoption_used() SQL function is a wrapper around the
<a href="c3ref/compileoption_get.html">sqlite3_compileoption_used()</a> C/C++ function.
When the argument X to sqlite_compileoption_used(X) is a string which
is the name of a compile-time option, this routine returns true (1) or
false (0) depending on whether or not that option was used during the
build.
</td></tr><tr><td valign="top" align="right" width="120"><a name="sqlite_source_id"></a>
sqlite_source_id()</td><td valign="top">
The sqlite_source_id() function returns a string that identifies the
specific version of the source code that was used to build the SQLite
library. The string returned by sqlite_source_id() begins with
the date and time that the source code was checked in and is follows by
an SHA1 hash that uniquely identifies the source tree. This function is
an SQL wrapper around the <a href="c3ref/libversion.html">sqlite3_sourceid()</a> C interface.
</td></tr><tr><td valign="top" align="right" width="120"><a name="sqlite_version"></a>
sqlite_version()</td><td valign="top">
The sqlite_version() function returns the version string for the SQLite
library that is running. This function is an SQL
wrapper around the <a href="c3ref/libversion.html">sqlite3_libversion()</a> C-interface.
</td></tr><tr><td valign="top" align="right" width="120"><a name="substr"></a>
substr(<i>X</i>,<i>Y</i>,<i>Z</i>)<br></br>substr(<i>X</i>,<i>Y</i>)</td><td valign="top">
The substr(X,Y,Z) function returns a substring of input string X that begins
with the Y-th character and which is Z characters long.
If Z is omitted then substr(X,Y) returns all characters through the end
of the string X beginning with the Y-th.
The left-most character of X is number 1. If Y is negative
then the first character of the substring is found by counting from the
right rather than the left. If Z is negative then
the abs(Z) characters preceding the Y-th character are returned.
If X is a string then characters indices refer to actual UTF-8
characters. If X is a BLOB then the indices refer to bytes.
</td></tr><tr><td valign="top" align="right" width="120"><a name="total_changes"></a>
total_changes()</td><td valign="top">
The total_changes() function returns the number of row changes
caused by INSERT, UPDATE or DELETE
statements since the current database connection was opened.
This function is a wrapper around the <a href="c3ref/total_changes.html">sqlite3_total_changes()</a>
C/C++ interface.
</td></tr><tr><td valign="top" align="right" width="120"><a name="trim"></a>
trim(<i>X</i>)<br></br>trim(<i>X</i>,<i>Y</i>)</td><td valign="top">
The trim(X,Y) function returns a string formed by removing any and all
characters that appear in Y from both ends of X.
If the Y argument is omitted, trim(X) removes spaces from both ends of X.
</td></tr><tr><td valign="top" align="right" width="120"><a name="typeof"></a>
typeof(<i>X</i>)</td><td valign="top">
The typeof(X) function returns a string that indicates the <a href="datatype3.html">datatype</a> of
the expression X: "null", "integer", "real", "text", or "blob".
</td></tr><tr><td valign="top" align="right" width="120"><a name="upper"></a>
upper(<i>X</i>)</td><td valign="top">
The upper(X) function returns a copy of input string X in which all
lower-case ASCII characters are converted to their upper-case equivalent.
</td></tr><tr><td valign="top" align="right" width="120"><a name="zeroblob"></a>
zeroblob(<i>N</i>)</td><td valign="top">
The zeroblob(N) function returns a BLOB consisting of N bytes of 0x00.
SQLite manages these zeroblobs very efficiently. Zeroblobs can be used to
reserve space for a BLOB that is later written using
<a href="c3ref/blob_open.html">incremental BLOB I/O</a>.
This SQL function is implemented using the <a href="c3ref/result_blob.html">sqlite3_result_zeroblob()</a>
routine from the C/C++ interface.
</td></tr>
</table>
|
