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This documentation is valid for Creatio version 7.16.0. We recommend using the newest version of Creatio documentation.

Retrieving data from the database

Glossary Item Box

Examples of using the Select class to retrieve data from the database

You can download the package with the configuration web service implementing the cases described below using the following link.

The query result handler method used in the cases
 
  
private string CreateJson(IDataReader dataReader)
{
    var list = new List<dynamic>();
    var cnt = dataReader.FieldCount;
    var fields = new List<string>();
    for (int i = 0; i < cnt; i++)
    {
        fields.Add(dataReader.GetName(i));
    }
    while (dataReader.Read())
    {
        dynamic exo = new System.Dynamic.ExpandoObject();
        foreach (var field in fields)
        {
            ((IDictionary<String, Object>)exo).Add(field, dataReader.GetColumnValue(field));
        }
        list.Add(exo);
    }
    return JsonConvert.SerializeObject(list);
}

Example 1

Receive the SQL query text.
 
  
public string GetSqlTextExample()
{
    var result = "";
    var select = new Select(UserConnection)
            .Column(Column.Asterisk())
        .From("Contact");
    result = select.GetSqlText();
    return result;
}

Example 2

Select a certain number of records from the needed table (object schema).
 
  
public string SelectColumns(string tableName, int top)
{
    top = top > 0 ? top : 1;
    var result = "{}";
    var select = new Select(UserConnection)
        .Top(top)
        .Column(Column.Asterisk())
        .From(tableName);
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 3

Select the identifier, the contacts’ names and birth dates (whose birth dates are later than the needed year)
 
  
public string SelectContactsYoungerThan(string birthYear)
{
    var result = "{}";
    var year = DateTime.ParseExact(birthYear, "yyyy", CultureInfo.InvariantCulture);
    var select = new Select(UserConnection)
            .Column("Id")
            .Column("Name")
            .Column("BirthDate")
        .From("Contact")
        .Where("BirthDate").IsGreater(Column.Parameter(year))
            .Or("BirthDate").IsNull()
        .OrderByDesc("BirthDate")
         as Select;
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 4

Select the identifier, the contacts’ names and birth dates (whose birth dates are later than the specified year and those who have the account names populated)
 
  
public string SelectContactsYoungerThanAndHasAccountId(string birthYear)
{
    var result = "{}";
    var year = DateTime.ParseExact(birthYear, "yyyy", CultureInfo.InvariantCulture);
    var select = new Select(UserConnection)
            .Column("Id")
            .Column("Name")
            .Column("BirthDate")
        .From("Contact")
        .Where()
        .OpenBlock("BirthDate").IsGreater(Column.Parameter(year))
            .Or("BirthDate").IsNull()
        .CloseBlock()
        .And("AccountId").Not().IsNull()
        .OrderByDesc("BirthDate")
         as Select;
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 5

Select the identifier and all contacts’ names having joined them to the identifiers and names of the corresponding accounts
 
  
public string SelectContactsJoinAccount()
{
    var result = "{}";
    var select = new Select(UserConnection)
            .Column("Contact", "Id").As("ContactId")
            .Column("Contact", "Name").As("ContactName")
            .Column("Account", "Id").As("AccountId")
            .Column("Account", "Name").As("AccountName")
        .From("Contact")
        .Join(JoinType.Inner, "Account")
            .On("Contact", "Id").IsEqual("Account", "PrimaryContactId")
         as Select;
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 6

Select the identifiers and names of the contacts that are primary for the accounts
 
  
public string SelectAccountPrimaryContacts()
{
    var result = "{}";
    var select = new Select(UserConnection)
            .Column("Id")
            .Column("Name")
        .From("Contact").As("C")
        .Where()
            .Exists(new Select(UserConnection)
                            .Column("A", "PrimaryContactId")
                        .From("Account").As("A")
                        .Where("A", "PrimaryContactId").IsEqual("C", "Id"))
         as Select;
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 7

Select the countries and the number of cities in a country, if such number is greater than the specified number
 
  
public string SelectCountriesWithCitiesCount(int count)
{
    var result = "{}";
    var select = new Select(UserConnection)
            .Column(Func.Count("City", "Id")).As("CitiesCount")
            .Column("Country", "Name").As("CountryName")
        .From("City")
        .Join(JoinType.Inner, "Country")
            .On("City", "CountryId").IsEqual("Country", "Id")
        .GroupBy("Country", "Name")
        .Having(Func.Count("City", "Id")).IsGreater(Column.Parameter(count))
        .OrderByDesc("CitiesCount")
         as Select;
    using (DBExecutor dbExecutor = UserConnection.EnsureDBConnection())
    {
        using (IDataReader dataReader = select.ExecuteReader(dbExecutor))
        {
            result = CreateJson(dataReader);
        }
    }
    return result;
}

Example 8

Receive the contact identifier by its name
 
  
public string SelectCountryIdByCityName(string CityName)
{
    var result = "";
    var select = new Select(UserConnection)
            .Column("CountryId")
        .From("City")
        .Where("Name").IsEqual(Column.Parameter(CityName)) as Select;
    result = select.ExecuteScalar<Guid>().ToString();
    return result;
}

See also:

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