SQLiteHelper aims to simplify the usage of SQLite in C#.
This small class (SQLiteHelper.cs) is built on top of System.Data.SQLite.DLL. A reference of this DLL must be added into your projects.
System.Data.SQLite.DLL
https://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki
- GetTableStatus
- GetTableList
- GetColumnStatus
- CreateTable
- UpdateTableStructure
- BeginTransaction, Commit, Rollback
- Select
- Execute
- ExecuteScalar
- Escape
- Insert
- Update
- LastInsertRowId
- RenameTable
- CopyAllData
- DropTable
- ShowDatabase
- AttachDatabase, DetachDatabase
Add this using statement at the top of your class:
using System.Data.SQLite;SQLiteConnection and SQLiteCommand have to be initialized before using SQLiteHelper:
Example:
using (SQLiteConnection conn = new SQLiteConnection("data source=C:\\data"))
{
using (SQLiteCommand cmd = new SQLiteCommand())
{
cmd.Connection = conn;
conn.Open();
SQLiteHelper sh = new SQLiteHelper(cmd);
// do something...
conn.Close();
}
}Get all information of tables in the database.
DataTable dt = sh.GetTableStatus();- GetTableList Get a list of tables in database.
DataTable dt = sh.GetTableList();
Get all information of columns in specific table.
// Get column's information from table "person"
DataTable dt = sh.GetColumnStatus("person");
Create table.
SQLiteTable tb = new SQLiteTable("person");
tb.Columns.Add(new SQLiteColumn("id", true));
tb.Columns.Add(new SQLiteColumn("name"));
tb.Columns.Add(new SQLiteColumn("membershipid", ColType.Integer));
tb.Columns.Add(new SQLiteColumn("level", ColType.Decimal, false, false, "5.5"));
sh.CreateTable(tb);
As the name said, it is used to update a table's structure. Maybe you have added new columns, or drop/deleted some columns. This method helps you to update it.
The process at code behind:
Assume that the old table is named: person The class creates a temporary table (named: person_temp) with your new defined structure. Copy all rows from person to person_temp. Drop/delete table of person. Rename table of person_temp to person Code example:
SQLiteTable tb = new SQLiteTable();
tb.Columns.Add(new SQLiteColumn("id", true));
tb.Columns.Add(new SQLiteColumn("name"));
tb.Columns.Add(new SQLiteColumn("sku"));
tb.Columns.Add(new SQLiteColumn("code"));
tb.Columns.Add(new SQLiteColumn("category"));
tb.Columns.Add(new SQLiteColumn("remarks"));
sh.UpdateTableStructure("person", tb);
What is transaction?
By default, every SQL query that is sent to SQLite database engine happens in a transaction. The engine automatically BEGIN a transaction and COMMIT it at the end. COMMIT is something like "Make it take effect".
If we send 3 SQL queries (INSERT, UPDATE, DELETE, etc...), 3 transactions are taken place. According to [SQLite official documentation - Frequently Asked Questions]:
"...A transaction normally requires two complete rotations of the disk platter, which on a 7200RPM disk drive limits you to about 60 transactions per second..."
Which means, with a 7200RPM hard disk, the best that we can do is 60 INSERTs (or UPDATE, DELETE, etc) per second.
But, If we manually issue a BEGIN TRANSACTION, all the queries will be wrapped in single transaction, then SQLite can execute huge amount of queries per second. Somebody said he can execute 10 million per second at [stackoverflow.com], but this is also depends on the speed of hard disk that you are using.
Code example with SQLiteHelper:
sh.BeginTransaction();
try
{
// INSERT.....
// INSERT.....
// UPDATE....
// ... skip for another 50,000 queries....
// DELETE....
// UPDATE...
// INSERT.....
sh.Commit();
}
catch
{
sh.Rollback();
}
ROLLBACK, in the above example means Cancel Transaction. All queries that have sent to SQLite database within that specific transaction are dismissed.
Return the query result in DataTable format.
Select(string sql)
Select(string sql, Dictionary<string, object> dicParameters = null)
Select(string sql, IEnumerable<SQLiteParameter> parameters = null)
Example 1:
DataTable dt = sh.Select("select * from person order by id;");
Example 2 (With parameters support):
var dic = new Dictionarystring, object();
dic["@aaa"] = 1;
dic["@bbb"] = 1;
DataTable dt = sh.Select("select * from member where membershipid = @aaa and locationid = @bbb;", dic);
Example 3 (With parameters support):
DataTable dt = sh.Select("select * from member where membershipid = @aaa and locationid = @bbb;",
new SQLiteParameter[] {
new SQLiteParameter("@aaa", 1),
new SQLiteParameter("@bbb", 1)
});
Execute single SQL query.
Execute(string sql)
Execute(string sql, Dictionary<string, object> dicParameters = null)
Execute(string sql, IEnumerable<SQLiteParameter> parameters = null)
Example:
sh.Execute("insert into person(name)values('hello');");
Return the result of first row first column in specific data type.
ExecuteScalar(string sql)
ExecuteScalar(string sql, Dictionary<string, object> dicParameters = null)
ExecuteScalar(string sql, IEnumerable<SQLiteParameter> parameters = null)
ExecuteScalar<datatype>(string sql)
ExecuteScalar<datatype>(string sql, Dictionary<string, object> dicParameters = null)
ExecuteScalar<datatype>(string sql, IEnumerable<SQLiteParameter> parameters = null)
Example:
string a = sh.ExecuteScalar<string>("select 'Hello!';");
int b = sh.ExecuteScalar<int>("select 1000;");
decimal c = sh.ExecuteScalar<decimal>("select 4.4;");
DateTime d = sh.ExecuteScalar<DateTime>("select date('now');");
byte[] e = sh.ExecuteScalar<byte[]>("select randomblob(16);");
Escape string sequence for text value to avoid SQL injection or invalid SQL syntax to be constructed.
sh.Execute("insert into person(name) values('" + Escape(input) + "');");
Insert new row of data. All data will be added as parameters at code behind. This support blob (byte[]) value too.
var dic = new Dictionary<string, object>();
dic["name"] = "John";
dic["membershipid"] = 1;
dic["level"] = 6.8;
sh.Insert("person", dic);
Update row. All data will be added as parameters at code behind. This support blob (byte[]) value too.
Example 1: Update with single condition (where id = 1)
var dicData = new Dictionary<string, object>();
dicData["name"] = "no name";
dicData["membershipid"] = 0;
dicData["level"] = 5.5;
sh.Update("person", dicData, "id", 1);
Example 2: Update with multiple condition (where membership = 1 and level = 5.5 and teamid = 1)
var dicData = new Dictionary<string, object>();
dicData["name"] = "no name";
dicData["status"] = 0;
dicData["money"] = 100;
dicData["dateregister"] = DateTime.MinValue;
var dicCondition = new Dictionary<string, object>();
dicCondition["membershipid"] = 1;
dicCondition["level"] = 5.5;
dicCondition["teamid"] = 1;
sh.Update("person", dicData, dicCondition);
Get the last issued id (Auto-Increment)
sh.Insert("person", dicData);
long id = sh.LastInsertRowId();
Rename a table.
sh.RenameTable("person", "person_backup");
Copy all data from one table to another.
sh.CopyAllData("person", "person_new");
Before copying, SQLiteHelper will scan the two tables for match columns. Only columns that exist in both tables will be copied.
Drop table, delete a table
sh.DropTable("person");
Display attached databases.
DataTable dt = sh.ShowDatabase();
Attach or detach a database
sh.AttachDatabase("C:\\data2013.sq3", "lastyeardb");
sb.DetachDatabase("lastyeardb");
That's it, guys/girls.
Happy coding :)
Lastly, I shall introduce other tools which you might consider when developing C#, VB.NET apps with SQLite:
- SQLite.NET
SQLite.NET is designed to make working with sqlite very easy in a .NET environment. It is an open source, minimal library to allow .NET and Mono applications to store data in [http://www.sqlite.org SQLite 3 databases]. It is written in C# and is meant to be simply compiled in with your projects. It was first designed to work with MonoTouch on the iPhone, but has grown up to work on all the platforms (Mono for Android, .NET, Silverlight, WP7, WinRT, Azure, etc.).
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