Summary of SQL basic syntax for C ＃

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This article is currently used for Visual Studio 2015 Platform SQLite3 , Other uses will be summarized later .

1. Use Nuget add to SQLite library

stay Visual Studio 2015 in , choice ： Tools -> NuGet Package manager -> Manage solutions NuGet Package

Search in this interface 「SQLite」, Choose to install one of them as needed SQLite library , It's better to be in the red box , A choice .

Then on the right side of the interface , Select the project you want to install to , After that, install it .

2. Common strategies

2.1 Catch exceptions

try
{
    // Put the statements that operate on the database in try in 
}
catch (Exception ex)
{
    // Handle exceptions 
}

2.2 Business and SQLite The code framework

// Use the following statement in conjunction with the specific SQL Just operate the statement 
// notes ： Do not actively control transactions , Every time you execute SQL The command will start the new transaction repeatedly ,
// Will be in SQL It takes a lot of time to operate . So there are a lot of insertions 、 Modify the operating 
// when , Proactively starting a transaction saves a lot of time 
var conn = new SQLiteConnection("Data Source = ./bitkyData.db; Version = 3; ");
conn.Open();
var trans = conn.BeginTransaction(); // Open transaction 
var cmd = conn.CreateCommand();
try
{
    // By manipulating the cmd, Use specific SQL Operation statement 
}
catch (Exception)
{
    trans.Rollback(); // Transaction rollback 
    // Perform specific exception handling 
}
trans.Commit();// Transaction submission 
conn.Close();// Connection is closed 

3. Required code block

3.1 Necessary initialization operations

// Specify the address of the database , as well as SQLite Version number 
SQLiteConnection conn = new SQLiteConnection("Data Source = ./bitkyData.db; Version = 3; ");

3.2 Insert the specified entry into the table

void insertData()
{
    conn.Open();
    var cmd = conn.CreateCommand();
    cmd.CommandText = "INSERT INTO ElectrodeController(typeA,typeB,typeM) VALUES (1, 2, 3)";
    cmd.ExecuteNonQuery();
    conn.Close();
}

3.3 Set the query criteria , Query the contents of the specified entry

static void selectData()
{
    conn.Open();
    var cmd = conn.CreateCommand();
    cmd.CommandText = "SELECT * FROM ElectrodeController where num > 45";
    var reader = cmd.ExecuteReader();// Get the result set 
    if (reader.HasRows)
    {
        while (reader.Read())
        {
            Debug.WriteLine("ID: " + reader.GetInt32(0));
        }
    }
    conn.Close();
}

3.4 Get the number of entries in the data table

static void getCount()
{
    conn.Open();
    var cmd = conn.CreateCommand();
    cmd.CommandText = "SELECT COUNT(*) FROM ElectrodeController";
    var scalar = cmd.ExecuteScalar();\\ Get the value of the first row and the first column in the result set 
    Debug.WriteLine("count: " + Convert.ToInt32(scalar));
    conn.Close();
}

4. Reference material

1. C# Inquire about SQL How many records are there in the database table
2. C# obtain SQL 2005 The total number of records in the table
3. C# , SQLite Batch operation speed optimization
4. C# operation Dataset The data set and SQLite database