SQLite

  int nVal, nSep;
  assert( argc==1 || argc==2 );
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  pAccum = (StrAccum*)sqlite3_aggregate_context(context, sizeof(*pAccum));

  if( pAccum ){
    sqlite3 *db = sqlite3_context_db_handle(context);
    int firstTerm = pAccum->nChar==0;
    pAccum->mxAlloc = db->aLimit[SQLITE_LIMIT_LENGTH];
    if( !firstTerm ){
      if( argc==2 ){
        zSep = (char*)sqlite3_value_text(argv[1]);
        nSep = sqlite3_value_bytes(argv[1]);
      }else{
        zSep = ",";
        nSep = 1;
      }
      if( zSep ) sqlite3_str_append(pAccum, zSep, nSep);
    }
    zVal = (char*)sqlite3_value_text(argv[0]);
    nVal = sqlite3_value_bytes(argv[0]);
    if( zVal ) sqlite3_str_append(pAccum, zVal, nVal);
  }
}
static void groupConcatInverse(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  int n;
  assert( argc==1 || argc==2 );
  StrAccum *pAccum;
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  pAccum = (StrAccum*)sqlite3_aggregate_context(context, sizeof(*pAccum));
  if( pAccum ){
    n = sqlite3_value_bytes(argv[0]);
    if( argc==2 ){
      n += sqlite3_value_bytes(argv[1]);
    }
    if( n>=pAccum->nChar ){
      pAccum->nChar = 0;
    }else{
      pAccum->nChar -= n;
      memmove(pAccum->zText, &pAccum->zText[n], pAccum->nChar);
    }
  }
}
static void groupConcatFinalize(sqlite3_context *context){
  StrAccum *pAccum;
  pAccum = sqlite3_aggregate_context(context, 0);
  if( pAccum ){
    if( pAccum->accError==SQLITE_TOOBIG ){
      sqlite3_result_error_toobig(context);

    VFUNCTION(last_insert_rowid, 0, 0, 0, last_insert_rowid),
    VFUNCTION(changes,           0, 0, 0, changes          ),
    VFUNCTION(total_changes,     0, 0, 0, total_changes    ),
    FUNCTION(replace,            3, 0, 0, replaceFunc      ),
    FUNCTION(zeroblob,           1, 0, 0, zeroblobFunc     ),
    FUNCTION(substr,             2, 0, 0, substrFunc       ),
    FUNCTION(substr,             3, 0, 0, substrFunc       ),
    WAGGREGATE(sum,   1,0,0, sumStep, sumFinalize, sumFinalize, sumInverse),
    WAGGREGATE(total, 1,0,0, sumStep, totalFinalize, totalFinalize, sumInverse),
    WAGGREGATE(avg,   1,0,0, sumStep, avgFinalize, avgFinalize, sumInverse),

    AGGREGATE2(count, 0,0,0, countStep, countFinalize, SQLITE_FUNC_COUNT  ),
    WAGGREGATE(count, 1,0,0, countStep, countFinalize, 0, 0 ),
    WAGGREGATE(group_concat, 1, 0, 0, groupConcatStep, 
        groupConcatFinalize, groupConcatValue, groupConcatInverse),
    WAGGREGATE(group_concat, 2, 0, 0, groupConcatStep, 
        groupConcatFinalize, groupConcatValue, groupConcatInverse),
  
    LIKEFUNC(glob, 2, &globInfo, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
#ifdef SQLITE_CASE_SENSITIVE_LIKE
    LIKEFUNC(like, 2, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
    LIKEFUNC(like, 3, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
#else
    LIKEFUNC(like, 2, &likeInfoNorm, SQLITE_FUNC_LIKE),

#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal, xValue) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(arg), 0, xStep,xFinal,xValue,0,#zName, {0}}
#define AGGREGATE2(zName, nArg, arg, nc, xStep, xFinal, extraFlags) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL)|extraFlags, \
   SQLITE_INT_TO_PTR(arg), 0, xStep,xFinal,xFinal,0,#zName, {0}}

#define WAGGREGATE(zName, nArg, arg, nc, xStep, xFinal, xValue, xInverse) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(arg), 0, xStep,xFinal,xValue,xInverse,#zName, {0}}

/*
** All current savepoints are stored in a linked list starting at
** sqlite3.pSavepoint. The first element in the list is the most recently
** opened savepoint. Savepoints are added to the list by the vdbe
** OP_Savepoint instruction.
*/

  }

  set ret
}

proc execsql_test {tn sql} {
  set res [execsql $sql]
  set sql [string map {string_agg group_concat} $sql]
  puts $::fd "do_execsql_test $tn {"
  puts $::fd "  [string trim $sql]"
  puts $::fd "} {$res}"
  puts $::fd ""
}

# Same as [execsql_test], except coerce all results to floating point values

  "
  execsql_test 1.$tn.13.5 "
    SELECT lag(b,b) OVER ( ORDER BY b%10,a $window ) FROM t2
  "
  execsql_test 1.$tn.13.6 "
    SELECT lag(b,b) OVER (PARTITION BY b%2,a ORDER BY b%10 $window) FROM t2
  "

  execsql_test 1.$tn.14.1 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER (ORDER BY a $window) FROM t2
  "

  execsql_test 1.$tn.14.2 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER (PARTITION BY b%10 ORDER BY a $window) FROM t2
  "
  execsql_test 1.$tn.14.3 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER ( ORDER BY b,a $window ) FROM t2
  "
  execsql_test 1.$tn.14.4 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER ( PARTITION BY b%10 ORDER BY b,a $window ) FROM t2
  "
  execsql_test 1.$tn.14.5 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER ( ORDER BY b%10,a $window ) FROM t2
  "
  execsql_test 1.$tn.14.6 "
    SELECT string_agg(CAST(b AS TEXT), '.') OVER (PARTITION BY b%2,a ORDER BY b%10 $window) FROM t2
  "
}

finish_test

}
execsql_test 2.3.2 {
  SELECT a, lag(b, 2) OVER (ORDER BY a) FROM t4
}
execsql_test 2.3.3 {
  SELECT a, lag(b, 3, 'abc') OVER (ORDER BY a) FROM t4
}

execsql_test 2.4.1 {
  SELECT string_agg(b, '.') OVER (
    ORDER BY a ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
  ) FROM t4
}

execsql_test 3.0 {
  DROP TABLE IF EXISTS t5;
  CREATE TABLE t5(a INTEGER PRIMARY KEY, b TEXT, c TEXT, d INTEGER);
  INSERT INTO t5 VALUES(1, 'A', 'one',   5);
  INSERT INTO t5 VALUES(2, 'B', 'two',   4);
  INSERT INTO t5 VALUES(3, 'A', 'three', 3);

  SELECT a, lag(b, 2) OVER (ORDER BY a) FROM t4
} {1 {}   2 {}   3 A   4 B   5 C   6 D   7 E   8 F   9 G   10 H}

do_execsql_test 2.3.3 {
  SELECT a, lag(b, 3, 'abc') OVER (ORDER BY a) FROM t4
} {1 abc   2 abc   3 abc   4 A   5 B   6 C   7 D   8 E   9 F   10 G}

do_execsql_test 2.4.1 {
  SELECT group_concat(b, '.') OVER (
    ORDER BY a ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
  ) FROM t4
} {A.B.C.D.E.F.G.H.I.J   B.C.D.E.F.G.H.I.J   C.D.E.F.G.H.I.J   D.E.F.G.H.I.J   E.F.G.H.I.J   F.G.H.I.J   G.H.I.J   H.I.J   I.J   J}

do_execsql_test 3.0 {
  DROP TABLE IF EXISTS t5;
  CREATE TABLE t5(a INTEGER PRIMARY KEY, b TEXT, c TEXT, d INTEGER);
  INSERT INTO t5 VALUES(1, 'A', 'one',   5);
  INSERT INTO t5 VALUES(2, 'B', 'two',   4);
  INSERT INTO t5 VALUES(3, 'A', 'three', 3);
  INSERT INTO t5 VALUES(4, 'B', 'four',  2);