如何在C＃中获取数据库（sql）表名和列以组合和列表框

Question

i'm trying to "play" with a small database and made a program that should connect to a database using info i give it (that part works fine)

after login another part of the program should connect to the database and do 2 things: 1. get all the table names and put it into a combobox 2. get all the column names of a table (choose form the combobox) and display them in a listbox

from that i plan to check a column name and use it to run different SQL commands on the tables

my problem is that i can't make it work

searched other examples from stackoverflow and google and i know i'm missing something small that makes this thing not work, but i don't know what.

ask for help from people with greater info then my own on this matter

for the combobox

    private void listTables()
    {
        const string query = "SELECT * FROM [dstut].sys.Tables";

        SqlConnection sqlConn = new SqlConnection(lw.ConnectionString);
        sqlConn.Open();

        SqlCommand cmd = new SqlCommand(query, sqlConn);
        SqlDataAdapter sda = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        sda.Fill(ds);
        List<string> l = new List<string>();
        foreach (DataRow dr in ds.Tables[0].Rows)
        {
            l.Add(dr[0].ToString());
        }
        cbTables.DataSource = l;
    }

    public DataSet GetAllColumns()
    {
        string query = "SELECT name FROM " + TableName;

        SqlConnection sqlConn = new SqlConnection(lw.ConnectionString);
        sqlConn.Open();
        SqlCommand cmd = new SqlCommand(query, sqlConn);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        foreach (DataRow dr in ds.Tables[0].Rows)
        {
            MessageBox.Show(Convert.ToString(dr["Field_1"]));
        }
        return ds;

    }

Answer 1

The first two sub section can be get it worked using following approach. And for the last part, you have to go with your own UI. Keep in mind, you are not the first person to create Query Expression Builder tool. So its worth checking or google for free/open source Query Expression Builder tools.

Use following query to return all tables from the connected database and bind it to your first combo.

SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE'

You can execute following query to return all columns from selected table from your first combo

SELECT COLUMN_NAME, * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='SelectedValueFromCombo1' ORDER BY ORDINAL_POSITION

Answer 2

I use SMO to pull down the information.

public class SqlDatabaseAdapter
{
    private readonly ServerConnection _serverConnection;

    public SqlDatabaseAdapter(string connectionString)
    {
        _serverConnection = new ServerConnection(new SqlConnection(connectionString));
    }

    public DataSet GetTables(string databaseName = "master")
    {
        var server = new Server(_serverConnection);
        var database = server.Databases.Cast<Database>().FirstOrDefault(d => d.Name == databaseName);

        var dataSet = new DataSet(databaseName);
        if (database == null) return dataSet;

        foreach (var table in database.Tables.Cast<Table>())
        {
            var dataTable = new DataTable(table.Name);

            FillColumns(table, dataTable);

            dataSet.Tables.Add(dataTable);
        }

        return dataSet;
    }

    public DataTable GetTable(string tableName, string databaseName = "master")
    {
        var server = new Server(_serverConnection);
        var database = server.Databases.Cast<Database>().FirstOrDefault(d => d.Name == databaseName);

        var dataTable = new DataTable(tableName);

        if (database == null) return dataTable;

        database.Refresh();

        var table = database.Tables.Cast<Table>().FirstOrDefault(f => f.Name == tableName);

        if (table == null) return dataTable;

        FillColumns(table, dataTable);

        return dataTable;
    }

    private static void FillColumns(Table table, DataTable dataTable)
    {
        foreach (Column column in table.Columns)
        {
            var type = ConvertToClrType(column.DataType.SqlDataType, column.Nullable);
            var dataColumn = new DataColumn(column.Name, type);

            dataTable.Columns.Add(dataColumn);
        }
    }

    private static Type ConvertToClrType(SqlDataType sqlDataType, bool nullable)
    {
        switch (sqlDataType)
        {
            case SqlDataType.BigInt:
                return nullable ? typeof (long?) : typeof (long);

            case SqlDataType.Binary:
            case SqlDataType.Image:
            case SqlDataType.Timestamp:
            case SqlDataType.VarBinary:
                return typeof (byte[]);

            case SqlDataType.Bit:
                return nullable ? typeof (bool?) : typeof (bool);

            case SqlDataType.Char:
            case SqlDataType.NChar:
            case SqlDataType.NText:
            case SqlDataType.NVarChar:
            case SqlDataType.Text:
            case SqlDataType.VarChar:
            case SqlDataType.Xml:
                return typeof (string);

            case SqlDataType.DateTime:
            case SqlDataType.SmallDateTime:
            case SqlDataType.Date:
            case SqlDataType.Time:
            case SqlDataType.DateTime2:
                return nullable ? typeof (DateTime?) : typeof (DateTime);

            case SqlDataType.Decimal:
            case SqlDataType.Money:
            case SqlDataType.SmallMoney:
            case SqlDataType.Numeric:
                return nullable ? typeof (decimal?) : typeof (decimal);

            case SqlDataType.Float:
                return nullable ? typeof (double?) : typeof (double);

            case SqlDataType.Int:
                return nullable ? typeof (int?) : typeof (int);

            case SqlDataType.Real:
                return nullable ? typeof (float?) : typeof (float);

            case SqlDataType.UniqueIdentifier:
                return nullable ? typeof (Guid?) : typeof (Guid);

            case SqlDataType.SmallInt:
                return nullable ? typeof (short?) : typeof (short);

            case SqlDataType.TinyInt:
                return typeof (byte?);

            case SqlDataType.Variant:
                return typeof (object);

            case SqlDataType.DateTimeOffset:
                return nullable ? typeof (DateTimeOffset?) : typeof (DateTimeOffset);

            default:
                throw new ArgumentOutOfRangeException("sqlDataType");
        }
    }
}