wasm/JS: documented DB.selectValue() and corrected the fetching of NULL columns via Stmt.get().

FossilOrigin-Name: 70f91fab825d365f505750acdb8d3ae532880c4cdb64d1e61bb21b24a115958b

2 files changed, 13 insertions, 3 deletions

diff --git a/ext/fiddle/sqlite3-api.js b/ext/fiddle/sqlite3-api.js
index 22773d8d7..7d30634f5 100644
--- a/ext/fiddle/sqlite3-api.js
+++ b/ext/fiddle/sqlite3-api.js
@@ -736,11 +736,18 @@
             this._udfs[name] = pUdf;
             return this;
         }/*createFunction()*/,
+        /**
+           Prepares the given SQL, step()s it one time and returns the
+           value of the first result column. If it has no results,
+           undefined is returned. If passed a second argument, it is
+           treated like an argument to Stmt.bind(), so may be any type
+           supported by that function. Throws on error (e.g. malformed
+           SQL).
+        */
         selectValue: function(sql,bind){
             let stmt, rc;
             try {
-                stmt = this.prepare(sql);
-                stmt.bind(bind);
+                stmt = this.prepare(sql).bind(bind);
                 if(stmt.step()) rc = stmt.get(0);
             }finally{
                 if(stmt) stmt.finalize();
@@ -1155,6 +1162,7 @@
             switch(undefined===asType
                    ? S.sqlite3_column_type(this._pStmt, ndx)
                    : asType){
+                case S.SQLITE_NULL: return null;
                 case S.SQLITE_INTEGER:{
                     return 0 | S.sqlite3_column_double(this._pStmt, ndx);
                     /* ^^^^^^^^ strips any fractional part and handles
diff --git a/ext/fiddle/testing1.js b/ext/fiddle/testing1.js
index 5e8dd662d..1c83b90e3 100644
--- a/ext/fiddle/testing1.js
+++ b/ext/fiddle/testing1.js
@@ -115,7 +115,9 @@ INSERT INTO t(a,b) VALUES(1,2),(3,4),(?,?);`,
             assert(3===db.selectValue("select bar(1,2)")).
             assert(-1===db.selectValue("select bar(1,2,-4)"));
 
-        T.assert('hi' === db.selectValue("select ?",'hi'));
+        T.assert('hi' === db.selectValue("select ?",'hi')).
+            assert(null===db.selectValue("select null"));
+                 
     }finally{
         db.close();
     }