Documentation Source Text

          {tailbranch
            {line ( {loop column-def ,} {loop {} {, table-constraint}} )}
            {line AS select-stmt}
          }
       }
  }
  column-def {
    line /column-name {or type-name nil} {loop nil {nil column-constraint nil}}
  }
  type-name {
     line {loop /name {}} {or {}
        {line ( signed-number )}
        {line ( signed-number , signed-number )}
     }
  }

             /collation-name
             {line {optx /database-name .}
                 {tailbranch /table-name /index-name}
             }
          }
  }
  select-stmt {
    stack
       {loop {line nil select-core nil} {nil compound-operator nil}}
       {optx ORDER BY {loop ordering-term ,}}
       {optx LIMIT /integer {optx {or OFFSET ,} /integer}}
  }
  select-core {
     stack
       {line SELECT {or nil DISTINCT ALL} {loop result-column ,}}
       {optx FROM join-source}
       {optx WHERE expr}
       {optx GROUP BY {loop ordering-term ,} {optx HAVING expr}}




        
  }
  result-column {
     or
        *
        {line /table-name . *}
        {line expr {optx {optx AS} /column-alias}}

  if {$y0 + 2*$RADIUS < $y1} {
    set xr0 [expr {$x-$RADIUS}]
    set xr1 [expr {$x+$RADIUS}]
    .c create arc $xr0 $y0 $xr1 [expr {$y0+2*$RADIUS}] \
          -width 2 -start 90 -extent -90 -tags $tag -style arc
    set yr0 [expr {$y0+$RADIUS}]
    set yr1 [expr {$y1-$RADIUS}]
    if {abs($yr1-$yr0)>$RADIUS*2} {
      set half_y [expr {($yr1+$yr0)/2}]
      .c create line $xr1 $yr0 $xr1 $half_y -width 2 -tags $tag -arrow last
      .c create line $xr1 $half_y $xr1 $yr1 -width 2 -tags $tag
    } else {
      .c create line $xr1 $yr0 $xr1 $yr1 -width 2 -tags $tag
    }
    .c create arc $xr0 [expr {$y1-2*$RADIUS}] $xr1 $y1 \
          -width 2 -start 0 -extent -90 -tags $tag -style arc
  } else { 
    set r [expr {($y1-$y0)/2.0}]
    set x0 [expr {$x-$r}]
    set x1 [expr {$x+$r}]
    .c create arc $x0 $y0 $x1 $y1 \
          -width 2 -start 90 -extent -180 -tags $tag -style arc
  }
}

# Draw a left-hand turn around.  Approximatley a "("
#
proc draw_left_turnback {tag x y0 y1 dir} {
  global RADIUS
  if {$y0 + 2*$RADIUS < $y1} {
    set xr0 [expr {$x-$RADIUS}]
    set xr1 [expr {$x+$RADIUS}]
    .c create arc $xr0 $y0 $xr1 [expr {$y0+2*$RADIUS}] \
          -width 2 -start 90 -extent 90 -tags $tag -style arc
    set yr0 [expr {$y0+$RADIUS}]
    set yr1 [expr {$y1-$RADIUS}]
    if {abs($yr1-$yr0)>$RADIUS*3} {
      set half_y [expr {($yr1+$yr0)/2}]
      if {$dir=="down"} {
        .c create line $xr0 $yr0 $xr0 $half_y -width 2 -tags $tag -arrow last
        .c create line $xr0 $half_y $xr0 $yr1 -width 2 -tags $tag
      } else {
        .c create line $xr0 $yr1 $xr0 $half_y -width 2 -tags $tag -arrow last
        .c create line $xr0 $half_y $xr0 $yr0 -width 2 -tags $tag
      }
    } else {
      .c create line $xr0 $yr0 $xr0 $yr1 -width 2 -tags $tag
    }
    # .c create line $xr0 $yr0 $xr0 $yr1 -width 2 -tags $tag
    .c create arc $xr0 [expr {$y1-2*$RADIUS}] $xr1 $y1 \
          -width 2 -start 180 -extent 90 -tags $tag -style arc
  } else { 
    set r [expr {($y1-$y0)/2.0}]
    set x0 [expr {$x-$r}]
    set x1 [expr {$x+$r}]
    .c create arc $x0 $y0 $x1 $y1 \

# Draw a sequence of terms from top to bottom.
#
proc draw_stack {indent lx} {
  global tagcnt RADIUS VSEP
  incr tagcnt
  set tag x$tagcnt

  set sep [expr {$VSEP*2}]
  set btm 0
  set n [llength $lx]
  set i 0
  set next_bypass_y 0

  foreach term $lx {
    set bypass_y $next_bypass_y
    if {$i>0 && $i<$n && [llength $term]>1 &&
        ([lindex $term 0]=="opt" || [lindex $term 0]=="optx")} {
      set bypass 1
      set term "line [lrange $term 1 end]"
    } else {
      set bypass 0
      set next_bypass_y 0
    }

    } else {
      set enter_y [expr {$btm - $ty0 + $sep*2 + 2}]
      if {$bypass} {set next_bypass_y [expr {$enter_y - $RADIUS}]}
      set enter_x [expr {$sep*2 + $indent}]
      set back_y [expr {$btm + $sep + 1}]
      if {$bypass_y>0} {
         set mid_y [expr {($bypass_y+$RADIUS+$back_y)/2}]
         .c create line $bypass_x $bypass_y $bypass_x $mid_y \
            -width 2 -tags $tag -arrow last
         .c create line $bypass_x $mid_y $bypass_x [expr {$back_y+$RADIUS}] \
             -tags $tag -width 2
      }
      .c move $t $enter_x $enter_y
      set e2 [expr {$exit_x + $sep}]
      .c create line $exit_x $exit_y $e2 $exit_y \
            -width 2 -tags $tag
      draw_right_turnback $tag $e2 $exit_y $back_y
      set e3 [expr {$enter_x-$sep}]
      set bypass_x [expr {$e3-$RADIUS}]
      set emid [expr {($e2+$e3)/2}]
      .c create line $e2 $back_y $emid $back_y \
                 -width 2 -tags $tag -arrow last
      .c create line $emid $back_y $e3 $back_y \
                 -width 2 -tags $tag
      set r2 [expr {($enter_y - $back_y)/2.0}]
      draw_left_turnback $tag $e3 $back_y $enter_y down
      .c create line $e3 $enter_y $enter_x $enter_y \
                 -arrow last -width 2 -tags $tag
      set exit_x [expr {$enter_x + $exx}]
      set exit_y [expr {$enter_y + $exy}]
    }
    .c addtag $tag withtag $t
    .c dtag $t $t
    set btm [lindex [.c bbox $tag] 3]
    incr i
  }
  if {$bypass} {
    set fwd_y [expr {$btm + $sep + 1}]
    set mid_y [expr {($next_bypass_y+$RADIUS+$fwd_y)/2}]
    set descender_x [expr {$exit_x+$RADIUS}]
    .c create line $bypass_x $next_bypass_y $bypass_x $mid_y \
        -width 2 -tags $tag -arrow last
    .c create line $bypass_x $mid_y $bypass_x [expr {$fwd_y-$RADIUS}] \
        -tags $tag -width 2
    .c create arc $bypass_x [expr {$fwd_y-2*$RADIUS}] \
                  [expr {$bypass_x+2*$RADIUS}] $fwd_y \
        -width 2 -start 180 -extent 90 -tags $tag -style arc
    .c create arc [expr {$exit_x-$RADIUS}] $exit_y \
                  $descender_x [expr {$exit_y+2*$RADIUS}] \
        -width 2 -start 90 -extent -90 -tags $tag -style arc
    .c create arc $descender_x [expr {$fwd_y-2*$RADIUS}] \
                  [expr {$descender_x+2*$RADIUS}] $fwd_y \
        -width 2 -start 180 -extent 90 -tags $tag -style arc
    set exit_x [expr {$exit_x+2*$RADIUS}]
    set half_x [expr {($exit_x+$indent)/2}]
    .c create line [expr {$bypass_x+$RADIUS}] $fwd_y $half_x $fwd_y \
        -width 2 -tags $tag -arrow last
    .c create line $half_x $fwd_y $exit_x $fwd_y \
        -width 2 -tags $tag
    .c create line $descender_x [expr {$exit_y+$RADIUS}] \
                   $descender_x [expr {$fwd_y-$RADIUS}] \
        -width 2 -tags $tag -arrow last
    set exit_y $fwd_y
  }
  set width [lindex [.c bbox $tag] 2]
  return [list $tag $exit_x $exit_y]
}

proc draw_loop {forward back} {
  global tagcnt
  incr tagcnt
  set tag x$tagcnt
  set sep $::HSEP
  set vsep $::VSEP
  if {$back==","} {
    set vsep 0
  } elseif {$back=="nil"} {
    set vsep [expr {$vsep/2}]
  }

  foreach {ft fexx fexy} [draw_diagram $forward] break
  foreach {fx0 fy0 fx1 fy1} [.c bbox $ft] break
  set fw [expr {$fx1-$fx0}]
  foreach {bt bexx bexy} [draw_backwards_line $back] break
  foreach {bx0 by0 bx1 by1} [.c bbox $bt] break
  set bw [expr {$bx1-$bx0}]

      .c create line $bexx $bexy $fx1 $bexy -width 2 -tags $bt -arrow first
      set mxx $fexx
    }
  } elseif {$bw>$fw} {
    set dx [expr {($bw-$fw)/2}]
    .c move $ft $dx 0
    set fexx [expr {$dx+$fexx}]
    .c create line 0 0 $dx $fexy -width 2 -tags $ft -arrow last
    .c create line $fexx $fexy $bx1 $fexy -width 2 -tags $ft
    set mxx $bexx
  }
  .c addtag $tag withtag $bt
  .c addtag $tag withtag $ft
  .c dtag $bt $bt
  .c dtag $ft $ft
  .c move $tag $sep 0
  set mxx [expr {$mxx+$sep}]
  .c create line 0 0 $sep 0 -width 2 -tags $tag
  draw_left_turnback $tag $sep 0 $biny up
  draw_right_turnback $tag $mxx $fexy $bexy
  foreach {x0 y0 x1 y1} [.c bbox $tag] break
  set exit_x [expr {$mxx+$::RADIUS}]
  .c create line $mxx $fexy $exit_x $fexy -width 2 -tags $tag
  return [list $tag $exit_x $fexy]
}

  .c addtag $tag withtag $bt
  .c addtag $tag withtag $ft
  .c dtag $bt $bt
  .c dtag $ft $ft
  .c move $tag $sep 0
  set mxx [expr {$mxx+$sep}]
  .c create line 0 0 $sep 0 -width 2 -tags $tag
  draw_left_turnback $tag $sep 0 $biny down
  draw_right_turnback $tag $mxx $fexy $bexy
  foreach {x0 y0 x1 y1} [.c bbox $tag] break
  .c create line $mxx $fexy $x1 $fexy -width 2 -tags $tag
  return [list $tag $x1 $fexy]
}

proc draw_or {lx} {

set syntax_linkage(delete-stmt) {{expr qualified-table-name} {create-trigger-stmt sql-stmt}}
set syntax_linkage(delete-stmt-limited) {{expr ordering-term qualified-table-name} sql-stmt}
set syntax_linkage(detach-stmt) {{} sql-stmt}
set syntax_linkage(drop-index-stmt) {{} sql-stmt}
set syntax_linkage(drop-table-stmt) {{} sql-stmt}
set syntax_linkage(drop-trigger-stmt) {{} sql-stmt}
set syntax_linkage(drop-view-stmt) {{} sql-stmt}
set syntax_linkage(expr) {{literal-value raise-function select-stmt type-name} {column-constraint create-trigger-stmt delete-stmt delete-stmt-limited insert-stmt join-constraint ordering-term result-column select-core table-constraint update-stmt update-stmt-limited}}
set syntax_linkage(foreign-key-clause) {{} {column-constraint table-constraint}}
set syntax_linkage(indexed-column) {{} {create-index-stmt table-constraint}}
set syntax_linkage(insert-stmt) {{expr select-stmt} {create-trigger-stmt sql-stmt}}
set syntax_linkage(join-constraint) {expr join-source}
set syntax_linkage(join-op) {{} join-source}
set syntax_linkage(join-source) {{join-constraint join-op single-source} {select-core single-source}}
set syntax_linkage(literal-value) {{} {column-constraint expr}}
set syntax_linkage(ordering-term) {expr {delete-stmt-limited select-core select-stmt update-stmt-limited}}
set syntax_linkage(pragma-stmt) {pragma-value sql-stmt}
set syntax_linkage(pragma-value) {signed-number pragma-stmt}
set syntax_linkage(qualified-table-name) {{} {delete-stmt delete-stmt-limited update-stmt update-stmt-limited}}
set syntax_linkage(raise-function) {{} expr}
set syntax_linkage(reindex-stmt) {{} sql-stmt}
set syntax_linkage(release-stmt) {{} sql-stmt}
set syntax_linkage(result-column) {expr select-core}
set syntax_linkage(rollback-stmt) {{} sql-stmt}
set syntax_linkage(savepoint-stmt) {{} sql-stmt}
set syntax_linkage(select-core) {{expr join-source ordering-term result-column} select-stmt}
set syntax_linkage(select-stmt) {{compound-operator ordering-term select-core} {create-table-stmt create-trigger-stmt create-view-stmt expr insert-stmt single-source sql-stmt}}
set syntax_linkage(signed-number) {{} {column-constraint pragma-value type-name}}
set syntax_linkage(single-source) {{join-source select-stmt} join-source}
set syntax_linkage(sql-stmt) {{alter-table-stmt analyze-stmt attach-stmt begin-stmt commit-stmt create-index-stmt create-table-stmt create-trigger-stmt create-view-stmt create-virtual-table-stmt delete-stmt delete-stmt-limited detach-stmt drop-index-stmt drop-table-stmt drop-trigger-stmt drop-view-stmt insert-stmt pragma-stmt reindex-stmt release-stmt rollback-stmt savepoint-stmt select-stmt update-stmt update-stmt-limited vacuum-stmt} sql-stmt-list}
set syntax_linkage(sql-stmt-list) {sql-stmt {}}
set syntax_linkage(table-constraint) {{conflict-clause expr foreign-key-clause indexed-column} create-table-stmt}
set syntax_linkage(type-name) {signed-number {column-def expr}}
set syntax_linkage(update-stmt) {{expr qualified-table-name} {create-trigger-stmt sql-stmt}}
set syntax_linkage(update-stmt-limited) {{expr ordering-term qualified-table-name} sql-stmt}
set syntax_linkage(vacuum-stmt) {{} sql-stmt}
set syntax_order {sql-stmt-list sql-stmt alter-table-stmt analyze-stmt attach-stmt begin-stmt commit-stmt rollback-stmt savepoint-stmt release-stmt create-index-stmt indexed-column create-table-stmt column-def type-name column-constraint signed-number table-constraint foreign-key-clause conflict-clause create-trigger-stmt create-view-stmt create-virtual-table-stmt delete-stmt delete-stmt-limited detach-stmt drop-index-stmt drop-table-stmt drop-trigger-stmt drop-view-stmt expr raise-function literal-value insert-stmt pragma-stmt pragma-value reindex-stmt select-stmt select-core result-column join-source single-source join-op join-constraint ordering-term compound-operator update-stmt update-stmt-limited qualified-table-name vacuum-stmt comment-syntax}

information.</p>  

<tcl>
###############################################################################
Section SELECT select {SELECT query}

BubbleDiagram select-stmt 1
BubbleDiagram select-core
BubbleDiagram result-column
BubbleDiagram join-source
BubbleDiagram single-source
BubbleDiagram join-op
BubbleDiagram join-constraint
BubbleDiagram ordering-term
BubbleDiagram compound-operator