How to create a new table in a database with program that uses entity framework? - sql

Question

I have a piece of software out in the field and I need to add a new table to it. I have the table in my entity framework and new clients get the table. How to I update the others?
ADDED: To make it clear my development and new clients have the table. How to update the older clients databases is the question?
Since it is in my model it seems I should just call a create method and everything should happen under the hood.
_context.NewTable.CreateTable();
But think that I will have to write a sql command string to see if table exists and if it doesn't to create the table.
IDVisitorEntities _context = new IDVisitorEntities ();
String cmd = IF NOT EXISTS ( SELECT [name]
FROM sys.tables
WHERE [name] = NewTable )
CREATE TABLE NewTable (
ID int IDENITY,
NAME VARCHAR(40))
_context.NewTable.CommandText (cmd);
I want to only run this one time if the table doesn't exist. So that doesn't solve that problem. I really don't know what to do.
ADDED 5/6/2013
I'm thinking that EF has the Property Collection for each table and that might hold a clue. Might have to use ICustomTypeDescriptor ... Anyone else have any thoughts?
Added 7/15/2013
I started building it, at my new job, here is a sample. I need to create a file(s) with the partial classes and have the abstract and interface applied to them. It has a long way to go but this is a start...
namespace DataModelMAXFM
{
public abstract class ATable
{
private ArrayList _columns = new ArrayList();
private ArrayList colsToAdd = new ArrayList();
public ArrayList Columns
{
get
{
return _columns;
}
}
public bool TableCreate(SqlConnection sqlConn)
{
//assuming table needs to be created (already checked)
//get column list
//use for loop to create query string
// run command
ITable thisItable;
if (Columns.Count <= 0) //generate column list if not already created
{
if (!ColumnList())
return false;
}
if (this is ITable)
{
thisItable = (ITable) this;
}
else
{
throw new Exception("");
}
StringBuilder sb = new StringBuilder("CREATE TABLE " + thisItable.GetTableName() + " (");
bool flgFirst = true; // to allow for proper comma placement
foreach (PropertyInfo prop in Columns)
{
String propType = this.GetDataType(prop);
if (propType == String.Empty)//check to make sure datatype found a match, EF to SQL
{
return false;
}
if (!flgFirst)
{
sb.Append(", ");
}
else
{
flgFirst = false;
}
sb.Append(prop.Name + " " + propType);
}
// add right parentheses
sb.Append(")");
//now run query created above
SqlCommand com;
try
{
com = new SqlCommand(sb.ToString(), sqlConn);
com.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine("TableCreate e:" + e.ToString());
return false;
}
return true;
}
public bool TableExists(SqlConnection sqlConn)
{
SqlDataReader sdr = null;
SqlCommand com;
ITable thisItable;
try
{
//create and execute command
if (this is ITable)
thisItable = (ITable)this;
else
{
throw new Exception("");
}
com = new SqlCommand("Select * from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = " + thisItable.GetTableName(), sqlConn);
sdr = com.ExecuteReader();
if (!sdr.HasRows)//ie table does not exist
{
return false;
}
}
catch (Exception e)
{
Console.WriteLine("TableCreate e:" + e.ToString());
return false;
}
//close datareader
try
{
sdr.Close();
}
catch (Exception e)
{
Console.WriteLine("close sqldatareader TableExists e: " + e.ToString());
}
return true;
}
public bool ColumnList()
{
bool flgListCreated = false;
PropertyInfo[] propList = typeof(TransactionCategory).GetProperties();
foreach (PropertyInfo prop in propList)
{
if (prop.CanRead && prop.CanWrite)
{
MethodInfo mget = prop.GetGetMethod(false);
MethodInfo mset = prop.GetSetMethod(false);
// Get and set methods have to be public
if (mget == null)
{
continue;
}
if (mset == null)
{
continue;
}
Columns.Add(prop);
if (!flgListCreated)
{
flgListCreated = true;
}
}
}
return flgListCreated;
}
public bool ColumnsExist(SqlConnection sqlConn)
{
ITable thisItable;
if (Columns.Count <= 0)
{
if (!ColumnList())
return false;
}
//2013-07-10 create basic connection and data reader
if (this is ITable)
thisItable = (ITable)this;
else
{
throw new Exception("");
}
SqlDataReader sdr = null;
SqlCommand com;
foreach (PropertyInfo prop in Columns)
{
try
{
//create and execute command
com = new SqlCommand("Select * from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = " + thisItable.GetTableName() + " and COLUMN_NAME = " + prop.Name, sqlConn);
sdr = com.ExecuteReader();
//if no rows returned to datareader == column does not exist, add to ArrayList of columns to add
if (!sdr.HasRows)
colsToAdd.Add(prop);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
return false;
}
}
//close datareader
try
{
sdr.Close();
}
catch (Exception e)
{
Console.WriteLine("close sqldatareader ColumnsExist e: " + e.ToString());
}
if (colsToAdd.Count == 0)
return false;
//returns true only if method worked and found columns to add to DB
return true;
}
public bool ColumnsCreate(SqlConnection sqlConn)
{
ITable thisItable;
StringBuilder sb = new StringBuilder();
if (colsToAdd.Count <= 0)
{
if (!ColumnsExist(sqlConn)) //2013-07-08 - MAXIMUS\58398(BJH) //if no columns, attempt to create list
return false; // if Column list was not created, return false
}
// add a array of the alter table
if (this is ITable)
thisItable = (ITable)this;
else
{
throw new Exception();
}
sb.Append("ALTER TABLE " + thisItable.GetTableName() + " ADD ( ");
bool flgFirst = true; // allows for no leading comma on first entry
String propType;
foreach (PropertyInfo prop in colsToAdd)
{
//make sure SQL datatype can be determined from EF data
propType = this.GetDataType(prop);
if (propType == String.Empty)
throw new Exception("no datatype match found " + prop.Name + " " + prop.PropertyType.ToString());
if (!flgFirst)
{
sb.Append(", ");
}
else
{
flgFirst = false;
}
sb.Append(prop.Name + " " + propType);
}
sb.Append(" )");
SqlCommand com;
try
{
com = new SqlCommand(sb.ToString(), sqlConn);
com.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
return false;
}
return true;
}
public bool ColumnsUpdate(SqlConnection sqlConn)
{
if (ColumnsExist(sqlConn))
return ColumnsCreate(sqlConn);
else
return false;
}
//method to convert from EF to SQL datatypes, see noted issues
public String GetDataType(PropertyInfo pi)
{
String s = "";
String pistr = pi.PropertyType.ToString();
switch (pistr)
{
case "Byte[]":
s = "binary";
break;
case "Boolean":
s = "bit";
break;
case "String Char[]": // also maps to other options such as nchar, ntext, nvarchar, text, varchar
s = "char";
break;
case "DateTime":
s = "datetime";
break;
case "DateTimeOffset":
s = "datetimeoffset";
break;
case "Decimal":
s = "decimal";
break;
case "Double":
s = "float";
break;
case "Int16":
s = "smallint";
break;
case "Int32":
s = "int";
break;
case "Int64":
s = "bigint";
break;
case "Single":
s = "real";
break;
case "TimeSpan":
s = "time";
break;
case "Byte":
s = "tinyint";
break;
case "Guid":
s = "uniqueidentifier";
break;
case "Xml":
s = "xml";
break;
default:
Console.WriteLine("No datatype match found for " + pi.ToString() + " " + pi.PropertyType.ToString());
return String.Empty;
}
return s;
}
}
public interface ITable
{
int ID
{
get;
}
bool TableUpdate(SqlConnection sqlConn);
bool TableStoredProceduresCreate(SqlConnection sqlConn);
bool TableStoredProceduresDrop(SqlConnection sqlConn);
bool TableCreateTriggers(SqlConnection sqlConn);
bool TableCreateViews(SqlConnection sqlConn);
DataTable GetDataTable();
DateTime dtTableImplemented
{
get;
}
String GetTableName();
}
}

Answer 1

How to I update the others?
And how do you upgrade code of others to require that table? Probably by using some patch or upgrade package and this package should create your table as well.
Since it is in my model it seems I should just call a create method and everything should happen under the hood.
No. EF itself has nothing to define database schema (Except creating SQL script for whole database creation). What you are looking for is possible with EF Migrations but that is feature of EF 4.3 and newer when using code first and DbContext API.