Schema Collections

The Schema collections return metadata for the Advanced SQL Engine objects. The notable metadata columns for the Interval Month data type are:

Column Name	Description
COLUMN_TYPE or DATA_TYPE	Set to INTERVAL MONTH.
FORMAT	Format assigned to the SQL Engine object.
PROVIDERDBTYPE	It is set to TdType.IntervalMonth.
INTERVAL_PRECISION	The maximum number of digits for the Month component.

Schema Table

The TdDataReader.SchemaTable returns result set metadata. The notable metadata columns for the Interval Month data type are:

Column Name	Description
NumericPrecision	The maximum number of digits for the Month component.
DataType	System.Type object for the System.String class.
ProviderType	Set to TdType.IntervalMonth.
Format	Format assigned to the SQL Engine object.
ProviderSpecificDataType	System.Type object for the TdIntervalMonth structure.

Configuring Parameters

The following example shows how to configure an Interval Month parameter using DbType type declaration and a Base Class Library (BCL) value.

Note
The Data Provider sends a VarChar data type to the SQL Engine when TdParameter.DbType is set to DbType.String. The SQL Engine will perform an implicit conversion to the Interval Month data type when required. The "SQL Functions, Operators, Expressions and Predicates" manual documents all implicit and explicit Data Type conversions.

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TdParameter deliveryInterval = new TdParameter(); deliveryInterval.ParameterName = "deliveryMonths"; deliveryInterval.DbType = DbType.String; // DBS will perform implicit conversion. deliveryInterval.Value = " 9";

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TdParameter deliveryInterval = new TdParameter();
deliveryInterval.ParameterName = "deliveryMonths";

deliveryInterval.DbType = DbType.String;

// DBS will perform implicit conversion.
deliveryInterval.Value = " 9";

The following example shows how to configure an Interval Month parameter using TdType type declaration and a Provider Specific value. The TdParameter.Precision property reflects the maximum number of digits for the Year component and it must be equal to or less than the target SQL Engine object (i.e. Column, Expression, Stored Procedure Parameters and etc.) declaration. The range of values are from One to Four. It is recommend to always set TdParameter.Precision property, however the Data Provider will utilize TdIntervalMonth.Precision property value when the TdParameter.Precision property is set to zero. .NET Applications can retrieve metadata from the Schema Collections or the Schema Table and apply the metadata to the TdParameter object.

Note
The Data Provider will throw an exception if the Interval value is greater than the maximum permissible value specified by the TdParameter.Precision property.

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TdParameter deliveryInterval = new TdParameter(); deliveryInterval.ParameterName = "deliveryMonths"; deliveryInterval.TdType = TdType.IntervalMonth; // Maximum number of digits for the Month component deliveryInterval.Precision = 2; deliveryInterval.ProviderSpecificValue = new TdIntervalMonth(9);

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TdParameter deliveryInterval = new TdParameter();
deliveryInterval.ParameterName = "deliveryMonths";

deliveryInterval.TdType = TdType.IntervalMonth;

// Maximum number of digits for the Month component
deliveryInterval.Precision = 2;

deliveryInterval.ProviderSpecificValue = new TdIntervalMonth(9);

Specifying Interval Month as Literal

The syntax for the Interval Month Literal is INTERVALsign'dddd'MONTH. Interval Month literals consist of the word Interval followed by optional negative sign, character string literal representation of the number of months (up to 4 digits) and the word Month.

Note
We recommend to always use Parameters in order to take advantage of the SQL Engine's Request Cache.

The following example shows 10 Months represented as Interval Month Literal in the Command Text.

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using (TdConnection cn = new TdConnection("data source=x;UserId=y;Password=z;")) { cn.Open(); TdCommand cmd = cn.CreateCommand(); // Delivery exceeding 10 months. cmd.CommandText = "SELECT Id, orderDate from Order where ((CURRENT_DATE - OrderDate) MONTH) > INTERVAL'10'MONTH "; using (TdDataReader reader = cmd.ExecuteReader()) { if (reader.HasRows) { while (reader.Read()) { Console.WriteLine("Id={0}", reader.GetInt64(0).ToString()); } } } }

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using (TdConnection cn = new TdConnection("data source=x;UserId=y;Password=z;"))
{
    cn.Open();
    TdCommand cmd = cn.CreateCommand();

    // Delivery exceeding 10 months.
    cmd.CommandText = "SELECT Id, orderDate from Order where ((CURRENT_DATE - OrderDate) MONTH) > INTERVAL'10'MONTH ";

    using (TdDataReader reader = cmd.ExecuteReader())
    {
        if (reader.HasRows)
        {
            while (reader.Read())
            {
                Console.WriteLine("Id={0}", reader.GetInt64(0).ToString());
            }
        }
    }
}

Retrieving Interval Month Data

The following methods and properties return the column or parameter value as a System.String structure.

The following methods and properties return the column or parameter value as a TdIntervalMonth structure.

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using (TdConnection cn = new TdConnection("data source=DS1;UserId=Joe;Password=XY;")) { cn.Open(); TdCommand cmd = cn.CreateCommand(); cmd.CommandText = "SELECT Id, orderDate, deliveryMonths from Order where deliveryMonths > ?"; cmd.Parameters.Add("deliveryMonthss", TdType.IntervalMonth); cmd.Parameters[0].Precison = 2; cmd.Parameters[0].Value = new TdIntervalMonth(2); using (TdDataReader reader = cmd.ExecuteReader()) { if (reader.HasRows) { while (reader.Read()) { Console.WriteLine("[String] Delivery Months = {0}", reader.GetString(2)); Console.WriteLine("[TdIntervalMonth] Delivery Months = {0}", reader.GetTdIntervalMonth(2).ToString()); } } } } /* Output: [String] Delivery Months = 3 [TdIntervalMonth] Delivery Months = 3 */

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using (TdConnection cn = new TdConnection("data source=DS1;UserId=Joe;Password=XY;"))
{
    cn.Open();

    TdCommand cmd = cn.CreateCommand();
    cmd.CommandText = "SELECT Id, orderDate, deliveryMonths from Order where deliveryMonths > ?";
    cmd.Parameters.Add("deliveryMonthss", TdType.IntervalMonth);
    cmd.Parameters[0].Precison = 2;
    cmd.Parameters[0].Value = new TdIntervalMonth(2);

    using (TdDataReader reader = cmd.ExecuteReader())
    {
        if (reader.HasRows)
        {
            while (reader.Read())
            {
                Console.WriteLine("[String] Delivery Months = {0}", reader.GetString(2));
                Console.WriteLine("[TdIntervalMonth] Delivery Months = {0}", reader.GetTdIntervalMonth(2).ToString());
            }
        }
    }
}

/* Output:
    [String] Delivery Months =  3
    [TdIntervalMonth] Delivery Months =  3
*/

Schema Collections

Schema Table

Configuring Parameters

Specifying Interval Month as Literal

Retrieving Interval Month Data

See Also