Documentation Source Text

  global nChng aChng xrefChng
  set aChng($nChng) [list $date $desc $options]
  set xrefChng($date) $nChng
  incr nChng
}

chng {2018-12-00 (3.26.0)} {
<li>Optimization: when doing an UPDATE on a table with [indexes on expressions],
    do not update the expression indexes if they do not refer to any of the columns
    of the table being updated.
<li>Added the [SQLITE_DBCONFIG_DEFENSIVE] option which disables the ability to 
    create corrupt database files using ordinary SQL.
<li>Added support for read-only [shadow tables] when the [SQLITE_DBCONFIG_DEFENSIVE]
    option is enabled.
<li>Added the [PRAGMA legacy_alter_table] command, which if enabled causes the
    [ALTER TABLE] command to behave like older version of SQLite (prior to
    version 3.25.0) for compatibility.
<li>Added [PRAGMA table_xinfo] that works just like [PRAGMA table_info]
    except thta is also shows hidden columns in virtual tables.
<li>Added the [https://sqlite.org/src/file/ext/misc/explain.c|explain virtual table]
    as a run-time loadable extension.
<li>Add a limit counter to the query planner to prevent excessive
    [sqlite3_prepare()] times for certain pathological SQL inputs.
<li>Added support for the [sqlite3_normalized_sql()] interface, when compiling
    with SQLITE_ENABLE_NORMALIZE.
<li>Enhanced triggers so that they can use [table-valued functions] that

But input lines that begin with a dot (".")
are intercepted and interpreted by the sqlite3 program itself.
These "dot commands" are typically used to change the output format
of queries, or to execute certain prepackaged query statements.
</p>

<p>
For a listing of the available dot commands, you can enter ".help"
at any time.  For example:

</p>

<tclscript>DisplayCode {
sqlite> (((.help)))
.archive ...           Manage SQL archives: ".archive --help" for details
.auth ON|OFF           Show authorizer callbacks
.backup ?DB? FILE      Backup DB (default "main") to FILE
                         Add "--append" to open using appendvfs.
.bail on|off           Stop after hitting an error.  Default OFF
.binary on|off         Turn binary output on or off.  Default OFF
.cd DIRECTORY          Change the working directory to DIRECTORY
.changes on|off        Show number of rows changed by SQL
.check GLOB            Fail if output since .testcase does not match
.clone NEWDB           Clone data into NEWDB from the existing database
.databases             List names and files of attached databases
.dbconfig ?op? ?val?   List or change sqlite3_db_config() options
.dbinfo ?DB?           Show status information about the database
.dump ?TABLE? ...      Dump the database in an SQL text format
                         If TABLE specified, only dump tables matching
                         LIKE pattern TABLE.
.echo on|off           Turn command echo on or off
.eqp on|off|full       Enable or disable automatic EXPLAIN QUERY PLAN
.excel                 Display the output of next command in a spreadsheet
.exit                  Exit this program
.expert                EXPERIMENTAL. Suggest indexes for specified queries
.fullschema ?--indent? Show schema and the content of sqlite_stat tables
.headers on|off        Turn display of headers on or off
.help                  Show this message
.import FILE TABLE     Import data from FILE into TABLE
.imposter INDEX TABLE  Create imposter table TABLE on index INDEX
.indexes ?TABLE?       Show names of all indexes
                         If TABLE specified, only show indexes for tables
                         matching LIKE pattern TABLE.
.iotrace FILE          Enable I/O diagnostic logging to FILE
.limit ?LIMIT? ?VAL?   Display or change the value of an SQLITE_LIMIT
.lint OPTIONS          Report potential schema issues. Options:
                         fkey-indexes     Find missing foreign key indexes
.load FILE ?ENTRY?     Load an extension library
.log FILE|off          Turn logging on or off.  FILE can be stderr/stdout
.mode MODE ?TABLE?     Set output mode where MODE is one of:
                         ascii    Columns/rows delimited by 0x1F and 0x1E
                         csv      Comma-separated values
                         column   Left-aligned columns.  (See .width)
                         html     HTML <table> code
                         insert   SQL insert statements for TABLE
                         line     One value per line
                         list     Values delimited by "|"
                         quote    Escape answers as for SQL
                         tabs     Tab-separated values
                         tcl      TCL list elements
.nullvalue STRING      Use STRING in place of NULL values
.once (-e|-x|FILE)     Output for the next SQL command only to FILE
                         or invoke system text editor (-e) or spreadsheet (-x)
                         on the output.
.open ?OPTIONS? ?FILE? Close existing database and reopen FILE
                         The --new option starts with an empty file
                         Other options: --readonly --append --zip
.output ?FILE?         Send output to FILE or stdout
.print STRING...       Print literal STRING
.prompt MAIN CONTINUE  Replace the standard prompts
.quit                  Exit this program
.read FILENAME         Execute SQL in FILENAME
.restore ?DB? FILE     Restore content of DB (default "main") from FILE
.save FILE             Write in-memory database into FILE
.scanstats on|off      Turn sqlite3_stmt_scanstatus() metrics on or off
.schema ?PATTERN?      Show the CREATE statements matching PATTERN
                          Add --indent for pretty-printing
.selftest ?--init?     Run tests defined in the SELFTEST table
.separator COL ?ROW?   Change the column separator and optionally the row
                         separator for both the output mode and .import
.session CMD ...       Create or control sessions
.sha3sum ?OPTIONS...?  Compute a SHA3 hash of database content
.shell CMD ARGS...     Run CMD ARGS... in a system shell
.show                  Show the current values for various settings
.stats ?on|off?        Show stats or turn stats on or off
.system CMD ARGS...    Run CMD ARGS... in a system shell
.tables ?TABLE?        List names of tables
                         If TABLE specified, only list tables matching
                         LIKE pattern TABLE.
.testcase NAME         Begin redirecting output to 'testcase-out.txt'
.timeout MS            Try opening locked tables for MS milliseconds
.timer on|off          Turn SQL timer on or off
.trace FILE|off        Output each SQL statement as it is run
.vfsinfo ?AUX?         Information about the top-level VFS
.vfslist               List all available VFSes
.vfsname ?AUX?         Print the name of the VFS stack
.width NUM1 NUM2 ...   Set column widths for "column" mode
                         Negative values right-justify
sqlite> 
}</tclscript>

<tcl>hd_fragment dotrules</tcl>
<h1>Rules for "dot-commands"</h1>

<p>Ordinary SQL statements are free-form, and can be

   geopoly_svg(geopoly_regular(x,y,40,n),
        printf('style="fill:none;stroke:%s;stroke-width:2"',color))
   || printf(' <text x="%d" y="%d" alignment-baseline="central" text-anchor="middle">%d</text>',x,y+6,n)
  FROM t1;
SELECT '</svg>';
</codeblock>

<tcl>hd_fragment regpoly geopoly_ccw</tcl>
<h2>The geopoly_ccw(J) Function</h2>

<p>The geopoly_ccw(J) function returns the polygon J with counter-clockwise (CCW) rotation.

<p>
[https://tools.ietf.org/html/rfc7946 | RFC-7946] requires that polygons use CCW rotation.
But the spec also observes that many legacy GeoJSON files do not following the spec and