Value Property (UniMacro)

In This Topic

Gets or sets macro value.

Syntax

Visual Basic
C#

'Declaration
 
Public Property Value As String

public string Value {get; set;}

Property Value

A string expression that macro evaluates to, if Condition is enabled.

Remarks

You can use other UniMacro objects from same UniMacroCollection as part of the expression returned.

Example

This example shows how to build a complex FROM clause depending on what DBMS is used.

csharp

UniConnection conn = new UniConnection();
//Connecting to MySQL server through MySQLDirect .NET
conn.ConnectionString = "provider=MySQL;Password=root;User Id=root;Host=localhost;Port=3307;";
//Define table name for all databases (blank condition)
//Note the single-line macro creation in the collection
conn.Macros.Add("tablename", "emp");
//For MySQL, prepend database name
conn.Macros.Add("tablename", "test.emp", "MySQL");
//Limit records count where it is easy (MySQL and PostgreSQL)
conn.Macros.Add("limit", "LIMIT 0,5", "mysql");
conn.Macros.Add("limit", "LIMIT 5 OFFSET 0", "PostgreSQL");
//Define default FROM clause
conn.Macros.Add("from", "FROM {tablename}");
//If the limit macro is defined, add extra clause
conn.Macros.Add("from", "FROM {tablename} {limit}", "limit");
//Define query that uses the macro
UniCommand cmd = new UniCommand("SELECT EName, Job, Sal {from}");
cmd.Connection = conn;
conn.Open();
try {
  UniDataReader dataReader = cmd.ExecuteReader();
  ...
  dataReader.Close();
}
finally {
  conn.Close();
}

Visual Basic

Dim conn As New UniConnection()
'Connecting to MySQL server through MySQLDirect .NET
conn.ConnectionString = "provider=MySQL;Password=root;User Id=root;Host=localhost;Port=3307;"
'Define table name for all databases (blank condition)
'Note the single-line macro creation in the collection
conn.Macros.Add("tablename", "emp")
'For MySQL, prepend database name
conn.Macros.Add("tablename", "test.emp", "MySQL")
'Limit records count where it is easy (MySQL and PostgreSQL)
conn.Macros.Add("limit", "LIMIT 0,5", "mysql")
conn.Macros.Add("limit", "LIMIT 5 OFFSET 0", "PostgreSQL")
'Define default FROM clause
conn.Macros.Add("from", "FROM {tablename}")
'If the limit macro is defined, add extra clause
conn.Macros.Add("from", "FROM {tablename} {limit}", "limit")
'Define query that uses the macro
Dim cmd As New UniCommand("SELECT EName, Job, Sal {from}")
cmd.Connection = conn
conn.Open()
Try
  'Run the query and make sure it is executed correctly
  Dim response As String = cmd.ExecuteScalar().ToString()
  MessageBox.Show(response)
Finally
  conn.Close()
  Dim dataReader As UniDataReader = cmd.ExecuteReader()
  ...
  dataReader.Close()
End Try

Reference

UniMacro Class
UniMacro Members
Condition Property
Name Property

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