cleanup SqlApi.cs and fix a disposable problem

BizHawk.Client.ApiHawk/Classes/Api/SqlApi.cs

@@ -1,17 +1,12 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using System.Data.SQLite;
 
 namespace BizHawk.Client.ApiHawk
 {
 	public sealed class SqlApi : ISql
 	{
-		public SqlApi() : base()
-		{ }
-
-		SQLiteConnection m_dbConnection;
-		string connectionString;
+		SQLiteConnection _dbConnection;
 
 		public string CreateDatabase(string name)
 		{
@@ -20,75 +15,76 @@ namespace BizHawk.Client.ApiHawk
 				SQLiteConnection.CreateFile(name);
 				return "Database Created Successfully";
 			}
-			catch (SQLiteException sqlEX)
+			catch (SQLiteException sqlEx)
 			{
-				return sqlEX.Message;
+				return sqlEx.Message;
 			}
-
 		}
 
 		public string OpenDatabase(string name)
 		{
 			try
 			{
-				SQLiteConnectionStringBuilder connBuilder = new SQLiteConnectionStringBuilder();
-				connBuilder.DataSource = name;
-				connBuilder.Version = 3; //SQLite version 
-				connBuilder.JournalMode = SQLiteJournalModeEnum.Wal;  //Allows for reads and writes to happen at the same time
-				connBuilder.DefaultIsolationLevel = System.Data.IsolationLevel.ReadCommitted;  //This only helps make the database lock left. May be pointless now
-				connBuilder.SyncMode = SynchronizationModes.Off; //This shortens the delay for do synchronous calls.
-				m_dbConnection = new SQLiteConnection(connBuilder.ToString());
-				connectionString = connBuilder.ToString();
-				m_dbConnection.Open();
-				m_dbConnection.Close();
+				var connBuilder = new SQLiteConnectionStringBuilder
+				{
+					DataSource = name,
+					Version = 3,
+					JournalMode = SQLiteJournalModeEnum.Wal,  // Allows for reads and writes to happen at the same time
+					DefaultIsolationLevel = System.Data.IsolationLevel.ReadCommitted, // This only helps make the database lock left. May be pointless now
+					SyncMode = SynchronizationModes.Off // This shortens the delay for do synchronous calls.
+				};
+
+				_dbConnection = new SQLiteConnection(connBuilder.ToString());
+				_dbConnection.Open();
+				_dbConnection.Close();
 				return "Database Opened Successfully";
 			}
-			catch (SQLiteException sqlEX)
+			catch (SQLiteException sqlEx)
 			{
-				return sqlEX.Message;
+				return sqlEx.Message;
 			}
 		}
 
 		public string WriteCommand(string query = "")
 		{
-			if (query == "")
+			if (string.IsNullOrWhiteSpace(query))
 			{
 				return "query is empty";
 			}
+
 			try
 			{
-				m_dbConnection.Open();
-				string sql = query;
-				SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
+				_dbConnection.Open();
+				var command = new SQLiteCommand(query, _dbConnection);
 				command.ExecuteNonQuery();
-				m_dbConnection.Close();
+				_dbConnection.Close();
 
 				return "Command ran successfully";
-
 			}
-			catch (NullReferenceException nullEX)
+			catch (NullReferenceException)
 			{
 				return "Database not open.";
 			}
-			catch (SQLiteException sqlEX)
+			catch (SQLiteException sqlEx)
 			{
-				m_dbConnection.Close();
-				return sqlEX.Message;
+				_dbConnection.Close();
+				return sqlEx.Message;
 			}
 		}
 
 		public dynamic ReadCommand(string query = "")
 		{
-			if (query == "")
+			if (string.IsNullOrWhiteSpace(query))
 			{
 				return "query is empty";
 			}
+
 			try
 			{
 				var table = new Dictionary<string, object>();
-				m_dbConnection.Open();
+				_dbConnection.Open();
 				string sql = $"PRAGMA read_uncommitted =1;{query}";
-				SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
+				using var command = new SQLiteCommand(sql, _dbConnection);
 				SQLiteDataReader reader = command.ExecuteReader();
 				bool rows = reader.HasRows;
 				long rowCount = 0;
@@ -97,32 +93,34 @@ namespace BizHawk.Client.ApiHawk
 				{
 					columns.Add(reader.GetName(i));
 				}
+
 				while (reader.Read())
 				{
 					for (int i = 0; i < reader.FieldCount; ++i)
 					{
 						table[$"{columns[i]} {rowCount}"] = reader.GetValue(i);
 					}
+
 					rowCount += 1;
 				}
+
 				reader.Close();
-				m_dbConnection.Close();
+				_dbConnection.Close();
 				if (rows == false)
 				{
 					return "No rows found";
 				}
 
 				return table;
-
 			}
 			catch (NullReferenceException)
 			{
 				return "Database not opened.";
 			}
-			catch (SQLiteException sqlEX)
+			catch (SQLiteException sqlEx)
 			{
-				m_dbConnection.Close();
-				return sqlEX.Message;
+				_dbConnection.Close();
+				return sqlEx.Message;
 			}
 		}
 	}