StartsWith, EndsWith, and Contains generated SQL behaves like the Sys…

…tem.String methods used to construct the query:

Contains is case sensitive, using instr() instead of like(). ToUpper() or ToLower can be used to compare without case sensitivity.
StartsWith and EndsWith is case sensitive unless a case insensitive StringComparison argument is passed using substr() = ? or the original like() depending upon case sensitivity

src/SQLite.cs

@@ -3001,17 +3001,53 @@ private CompileResult CompileExpr (Expression expr, List<object> queryArgs)
 				}
 				else if (call.Method.Name == "Contains" && args.Length == 1) {
 					if (call.Object != null && call.Object.Type == typeof(string)) {
-						sqlCall = "(" + obj.CommandText + " like ('%' || " + args [0].CommandText + " || '%'))";
+						sqlCall = "( instr(" + obj.CommandText + "," + args [0].CommandText + ") >0 )";
 					}
 					else {
 						sqlCall = "(" + args [0].CommandText + " in " + obj.CommandText + ")";
 					}
 				}
-				else if (call.Method.Name == "StartsWith" && args.Length == 1) {
-					sqlCall = "(" + obj.CommandText + " like (" + args [0].CommandText + " || '%'))";
-				}
-				else if (call.Method.Name == "EndsWith" && args.Length == 1) {
-					sqlCall = "(" + obj.CommandText + " like ('%' || " + args [0].CommandText + "))";
+				else if (call.Method.Name == "StartsWith" && args.Length >= 1)
+				{
+				    var startsWithCmpOp = StringComparison.CurrentCulture;
+				    if (args.Length == 2)
+				    {
+                        startsWithCmpOp = (StringComparison) args[1].Value;
+                    }
+				    switch (startsWithCmpOp)
+				    {
+				        case StringComparison.Ordinal:
+				        case StringComparison.CurrentCulture:
+				        case StringComparison.InvariantCulture:
+                            sqlCall = "( substr(" + obj.CommandText + ", 1, " + args[0].Value.ToString().Length + ") =  " + args[0].CommandText + ")";
+                                break;
+				        case StringComparison.OrdinalIgnoreCase:
+				        case StringComparison.CurrentCultureIgnoreCase:
+				        case StringComparison.InvariantCultureIgnoreCase:
+                            sqlCall = "(" + obj.CommandText + " like (" + args[0].CommandText + " || '%'))";
+                                break;
+				    }
+
+                }
+                else if (call.Method.Name == "EndsWith" && args.Length >= 1) {
+				    var endsWithCmpOp = StringComparison.CurrentCulture;
+				    if (args.Length == 2)
+				    {
+				        endsWithCmpOp = (StringComparison)args[1].Value;
+				    }
+				    switch (endsWithCmpOp)
+				    {
+				        case StringComparison.Ordinal:
+				        case StringComparison.CurrentCulture:
+				        case StringComparison.InvariantCulture:
+                            sqlCall = "( substr(" + obj.CommandText + ", length(" + obj.CommandText + ") - "+args[0].Value.ToString().Length+ "+1, " + args[0].Value.ToString().Length + ") =  " + args[0].CommandText + ")";
+				            break;
+				        case StringComparison.OrdinalIgnoreCase:
+				        case StringComparison.CurrentCultureIgnoreCase:
+				        case StringComparison.InvariantCultureIgnoreCase:
+                            sqlCall = "(" + obj.CommandText + " like ('%' || " + args[0].CommandText + "))";
+                            break;
+				    }
 				}
 				else if (call.Method.Name == "Equals" && args.Length == 1) {
 					sqlCall = "(" + obj.CommandText + " = (" + args[0].CommandText + "))";

tests/StringQueryTest.cs

@@ -62,29 +62,49 @@ public void StartsWith ()
 		{
 			var fs = db.Table<Product> ().Where (x => x.Name.StartsWith ("F")).ToList ();
 			Assert.AreEqual (2, fs.Count);
-
-			var bs = db.Table<Product> ().Where (x => x.Name.StartsWith ("B")).ToList ();
+
+		    var lfs = db.Table<Product>().Where(x => x.Name.StartsWith("f")).ToList();
+		    Assert.AreEqual(0, lfs.Count);
+
+
+		    var lfs2 = db.Table<Product>().Where(x => x.Name.StartsWith("f",StringComparison.OrdinalIgnoreCase)).ToList();
+		    Assert.AreEqual(2, lfs2.Count);
+
+
+            var bs = db.Table<Product> ().Where (x => x.Name.StartsWith ("B")).ToList ();
 			Assert.AreEqual (1, bs.Count);
 		}
 
 		[Test]
 		public void EndsWith ()
 		{
 			var fs = db.Table<Product> ().Where (x => x.Name.EndsWith ("ar")).ToList ();
-			Assert.AreEqual (2, fs.Count);
-
-			var bs = db.Table<Product> ().Where (x => x.Name.EndsWith ("o")).ToList ();
+		    Assert.AreEqual (2, fs.Count);
+
+		    var lfs = db.Table<Product>().Where(x => x.Name.EndsWith("Ar")).ToList();
+		    Assert.AreEqual(0, lfs.Count);
+
+            var bs = db.Table<Product> ().Where (x => x.Name.EndsWith ("o")).ToList ();
 			Assert.AreEqual (1, bs.Count);
 		}
 
 		[Test]
 		public void Contains ()
 		{
-			var fs = db.Table<Product> ().Where (x => x.Name.Contains ("o")).ToList ();
-			Assert.AreEqual (2, fs.Count);
-
-			var bs = db.Table<Product> ().Where (x => x.Name.Contains ("a")).ToList ();
+		    var fs = db.Table<Product>().Where(x => x.Name.Contains("o")).ToList();
+		    Assert.AreEqual(2, fs.Count);
+
+            var lfs = db.Table<Product> ().Where (x => x.Name.Contains ("O")).ToList ();
+			Assert.AreEqual (0, lfs.Count);
+
+		    var lfsu = db.Table<Product>().Where(x => x.Name.ToUpper().Contains("O")).ToList();
+		    Assert.AreEqual(2, lfsu.Count);
+
+            var bs = db.Table<Product> ().Where (x => x.Name.Contains ("a")).ToList ();
 			Assert.AreEqual (2, bs.Count);
-		}
+
+		    var zs = db.Table<Product>().Where(x => x.Name.Contains("z")).ToList();
+		    Assert.AreEqual(0, zs.Count);
+        }
 	}
 }