SQLite

     functions, its read-only `pointer` property holds its `sqlite3_stmt*`
     pointer value.

     Other non-function properties include:

     - `db`: the DB object which created the statement.

     - `columnCount`: the number of result columns in the query, or 0
     for queries which cannot return results. This property is a proxy
     for sqlite3_column_count() and its use in loops should be avoided
     because of the call overhead associated with that. The
     `columnCount` is not cached when the Stmt is created because a
     schema change made via a separate db connection between this
     statement's preparation and when it is stepped may invalidate it.

     - `parameterCount`: the number of bindable parameters in the query.
  */
  const Stmt = function(){
    if(BindTypes!==arguments[2]){
      toss3(capi.SQLITE_MISUSE, "Do not call the Stmt constructor directly. Use DB.prepare().");
    }
    this.db = arguments[0];
    __ptrMap.set(this, arguments[1]);

    this.parameterCount = capi.sqlite3_bind_parameter_count(this.pointer);
  };

  /** Throws if the given DB has been closed, else it is returned. */
  const affirmDbOpen = function(db){
    if(!db.pointer) toss3("DB has been closed.");
    return db;

       result set are stored in this array before the callback (if
       any) is triggered (regardless of whether the query produces any
       result rows). If no statement has result columns, this value is
       unchanged. Achtung: an SQL result may have multiple columns
       with identical names.

       - `callback` = a function which gets called for each row of the
       result set, but only if that statement has any result rows. The
       callback's "this" is the options object, noting that this
       function synthesizes one if the caller does not pass one to
       exec(). The second argument passed to the callback is always
       the current Stmt object, as it's needed if the caller wants to
       fetch the column names or some such (noting that they could
       also be fetched via `this.columnNames`, if the client provides
       the `columnNames` option). If the callback returns a literal
       `false` (as opposed to any other falsy value, e.g. an implicit
       `undefined` return), any ongoing statement-`step()` iteration
       stops without an error. The return value of the callback is
       otherwise ignored.

       ACHTUNG: The callback MUST NOT modify the Stmt object. Calling
       any of the Stmt.get() variants, Stmt.getColumnName(), or
       similar, is legal, but calling step() or finalize() is
       not. Member methods which are illegal in this context will
       trigger an exception, but clients must also refrain from using
       any lower-level (C-style) APIs which might modify the
       statement.

       The first argument passed to the callback defaults to an array of
       values from the current result row but may be changed with ...

       - `rowMode` = specifies the type of he callback's first argument.
       It may be any of...

       A) A string describing what type of argument should be passed
       as the first argument to the callback:

         A.1) `'array'` (the default) causes the results of
         `stmt.get([])` to be passed to the `callback` and/or appended
         to `resultRows`.

         A.2) `'object'` causes the results of
         `stmt.get(Object.create(null))` to be passed to the
         `callback` and/or appended to `resultRows`.  Achtung: an SQL
         result may have multiple columns with identical names. In
         that case, the right-most column will be the one set in this
         object!

         A.3) `'stmt'` causes the current Stmt to be passed to the
         callback, but this mode will trigger an exception if
         `resultRows` is an array because appending the transient
         statement to the array would be downright unhelpful.

       B) An integer, indicating a zero-based column in the result
       row. Only that one single value will be passed on.

       C) A string with a minimum length of 2 and leading character of
       '$' will fetch the row as an object, extract that one field,
       and pass that field's value to the callback. Note that these

          if(saveSql) saveSql.push(capi.sqlite3_sql(pStmt).trim());
          stmt = new Stmt(this, pStmt, BindTypes);
          if(bind && stmt.parameterCount){
            stmt.bind(bind);
            bind = null;
          }
          if(evalFirstResult && stmt.columnCount){
            /* Only forward SELECT-style results for the FIRST query
               in the SQL which potentially has them. */
            let gotColNames = Array.isArray(
              opt.columnNames
              /* As reported in
                 https://sqlite.org/forum/forumpost/7774b773937cbe0a
                 we need to delay fetching of the column names until
                 after the first step() (if we step() at all) because
                 a schema change between the prepare() and step(), via
                 another connection, may invalidate the column count
                 and names. */) ? 0 : 1;
            evalFirstResult = false;



            if(arg.cbArg || resultRows){
              for(; stmt.step(); stmt._isLocked = false){
                if(0===gotColNames++) stmt.getColumnNames(opt.columnNames);
                stmt._isLocked = true;
                const row = arg.cbArg(stmt);
                if(resultRows) resultRows.push(row);
                if(callback && false === callback.call(opt, row, stmt)){
                  break;
                }
              }
              stmt._isLocked = false;
            }
            if(0===gotColNames){
              /* opt.columnNames was provided but we visited no result rows */
              stmt.getColumnNames(opt.columnNames);
            }
          }else{
            stmt.step();
          }
          stmt.finalize();
          stmt = null;
        }
      }/*catch(e){

    finalize: function(){
      if(this.pointer){
        affirmUnlocked(this,'finalize()');
        delete __stmtMap.get(this.db)[this.pointer];
        capi.sqlite3_finalize(this.pointer);
        __ptrMap.delete(this);
        delete this._mayGet;

        delete this.parameterCount;
        delete this.db;
        delete this._isLocked;
      }
    },
    /** Clears all bound values. Returns this object.
        Throws if this statement has been finalized. */

    */
    get: function(ndx,asType){
      if(!affirmStmtOpen(this)._mayGet){
        toss3("Stmt.step() has not (recently) returned true.");
      }
      if(Array.isArray(ndx)){
        let i = 0;
        const n = this.columnCount;
        while(i<n){
          ndx[i] = this.get(i++);
        }
        return ndx;
      }else if(ndx && 'object'===typeof ndx){
        let i = 0;
        const n = this.columnCount;
        while(i<n){
          ndx[capi.sqlite3_column_name(this.pointer,i)] = this.get(i++);
        }
        return ndx;
      }
      affirmColIndex(this, ndx);
      switch(undefined===asType
             ? capi.sqlite3_column_type(this.pointer, ndx)

    */
    getColumnName: function(ndx){
      return capi.sqlite3_column_name(
        affirmColIndex(affirmStmtOpen(this),ndx).pointer, ndx
      );
    },
    /**
       If this statement potentially has result columns, this function
       returns an array of all such names. If passed an array, it is
       used as the target and all names are appended to it. Returns
       the target array. Throws if this statement cannot have result
       columns. This object's columnCount property holds the number of
       columns.
    */
    getColumnNames: function(tgt=[]){
      affirmColIndex(affirmStmtOpen(this),0);
      const n = this.columnCount;
      for(let i = 0; i < n; ++i){
        tgt.push(capi.sqlite3_column_name(this.pointer, i));
      }
      return tgt;
    },
    /**
       If this statement has named bindable parameters and the
       given name matches one, its 1-based bind index is

      enumerable: true,
      get: function(){return __ptrMap.get(this)},
      set: ()=>toss3("The pointer property is read-only.")
    }
    Object.defineProperty(Stmt.prototype, 'pointer', prop);
    Object.defineProperty(DB.prototype, 'pointer', prop);
  }
  /**
     Stmt.columnCount is an interceptor for sqlite3_column_count().

     This requires an unfortunate performance hit compared to caching
     columnCount when the Stmt is created/prepared (as was done in
     SQLite <=3.42.0), but is necessary in order to handle certain
     corner cases, as described in
     https://sqlite.org/forum/forumpost/7774b773937cbe0a.
  */
  Object.defineProperty(Stmt.prototype, 'columnCount', {
    enumerable: false,
    get: function(){return capi.sqlite3_column_count(this.pointer)},
    set: ()=>toss3("The columnCount property is read-only.")
  });

  /** The OO API's public namespace. */
  sqlite3.oo1 = {
    DB,
    Stmt
  }/*oo1 object*/;

        if( ! m ) continue;
        args[decodeURIComponent(m[1])] = (m[3] ? decodeURIComponent(m[3]) : true);
      }
      return args;
    }
  };


  /**
     This is a module object for use with the emscripten-installed
     sqlite3InitModule() factory function.
  */
  self.sqlite3TestModule = {
    /**
       Array of functions to call after Emscripten has initialized the

          .assert(1===this.db.openStatementCount())
          .assert(
            capi.sqlite3_stmt_status(
              st, capi.SQLITE_STMTSTATUS_RUN, 0
            ) === 0)
          .assert(!st._mayGet)
          .assert('a' === st.getColumnName(0))
          .mustThrowMatching(()=>st.columnCount=2,
                             /columnCount property is read-only/)
          .assert(1===st.columnCount)
          .assert(0===st.parameterCount)
          .mustThrow(()=>st.bind(1,null))
          .assert(true===st.step())
          .assert(3 === st.get(0))
          .mustThrow(()=>st.get(1))
          .mustThrow(()=>st.get(0,~capi.SQLITE_INTEGER))

        columnNames: colNames,
        _myState: 3 /* Accessible from the callback */,
        callback: function(row,stmt){
          ++counter;
          T.assert(
            3 === this._myState
            /* Recall that "this" is the options object. */
          ).assert(
            this.columnNames===colNames
          ).assert(
            this.columnNames[0]==='a' && this.columnNames[1]==='b'


          ).assert(
            (row.a%2 && row.a<6) || 'blob'===row.a
          );
        }
      });
      T.assert(2 === colNames.length)
        .assert('a' === colNames[0])
        .assert(4 === counter)
        .assert(4 === list.length);
      colNames = [];
      db.exec({
        /* Ensure that columnNames is populated for empty result sets. */
        sql: "SELECT a a, b B FROM t WHERE 0",
        columnNames: colNames
      });
      T.assert(2===colNames.length)
        .assert('a'===colNames[0] && 'B'===colNames[1]);
      list.length = 0;
      db.exec("SELECT a a, b b FROM t",{
        rowMode: 'array',
        callback: function(row,stmt){
          ++counter;
          T.assert(Array.isArray(row))
            .assert((0===row[1]%2 && row[1]<7)

           https://github.com/emscripten-core/emscripten/issues/17391 */
        T.mustThrow(()=>db.selectValue("SELECT "+(Number.MAX_SAFE_INTEGER+1))).
          mustThrow(()=>db.selectValue("SELECT "+(Number.MIN_SAFE_INTEGER-1)));
      }

      let st = db.prepare("update t set b=:b where a='blob'");
      try {
        T.assert(0===st.columnCount);
        const ndx = st.getParamIndex(':b');
        T.assert(1===ndx);
        st.bindAsBlob(ndx, "ima blob").reset(true);
      } finally {
        st.finalize();
      }