I looked at SQLServerdal at noon and painted a picture.
SQL data access layer is designed for SQLServer databases. This layer is the bottom of the entire project!
SQLHELPER encapsulates the access function of data through a set of static methods.
(DAAB.NET SQLHELPER complete code is all printed, deleting a total of 21 pages of comments. Leave less less than a class.)
The SQLHELPER.CS class is an Account.cs, Inventory.cs, item.cs, orde.cs, product.cs, profile.cs six class base classes. They all call the SQLHELPER.CS class for functional operations.
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[1] SQLSERVERDAL core -> SQLHELPER.CS Today's soft test, Zhu Ge net test! ~~ Date: 2005-11-5 Continue to see ...
SQLHELPER consists of the following static methods. From:
public
Static
int
ExecutenonQuery ()
public
Static
SqlDataReader ExecuteReader ()
public
Static
Object
Executescalar ()
public
Static
Void
Cacheparameters ()
public
Static
Sqlparameter [] getCachedParameters ()
Private
Static
Void
PrepareCommand ()
Let's take a look at prepareCommand (). Because ExecuteNonQuery (), ExecuteReader (), ExecuteScalar () is called prepareCommand ()!
Private
Static
Void
PrepareCommand (SqlCommand CMD, SqlTransaction Conn, Sqltransaction Trans, CommandType CMDTYPE,
String
cmdtext, SQLParameter [] cmdparms)
{// Connection status Open if (Conn.State! = ConnectionsTate.Open) Conn (); cmd.connection = conn; cmd.commandtext = cmdText; // Transact-SQL Transaction IF (Trans! = NULL) CMD .Transaction = Trans; cmd.commandtype = cmdtype; if (cmdparms! = Null) {Foreach (Sqlparameter Parm in cmdparms) cmd.parameters.add (PARM);}}
PREPARCOMMAND () has 6 parameters
SQLCOMMAND CMD, // To execute SQL statement or stored procedure
SqlConnection conn, // database connection string
SQLTransaction Trans, // Database transaction
CommandType cmdtype, // Perform the type of the database text or storedprocedure
String cmdtext, // SQL statement (stored procedure, and t-sql command) SQLParameter [] cmdparms // sqlcommand parameters
PrepareCommand mainly determines if the database status is open, if the status is turned off, open the database. Database transaction TRANS is not empty, if it does not perform transaction operations for freeware. Alternately return some parameters.
Let's take a look at CacheParameters () first stated in the SQLHELPER class, the domain is primarily used to store the parameters of SQL (CMDPARMS). It will be used in cacheparameters ().
public
Static
Void
Cacheparameters
String
CacheKey,
//
Buffer logo keyword
Params
Sqlparameter [] cmdparms)
//
SQL parameter array
{PARMCACHE [CacheKey] = cmdparms;
SQLHELPER also defines a getting cache parameter method GetCacheParameters () for getting buffered SQL parameters from cache.
public
Static
Sqlparameter [] getCachedParameters
String
Cachekey)
{SqlParameter [] cachedParms = (SqlParameter []) parmCache [cacheKey]; // null if the cache if (cachedParms == null) return to nll return null; SqlParameter [] clonedParms = new SqlParameter [cachedParms.Length]; / / Copy the parameters in cache for (int i = 0, j = cachedparms.lend; i Simply read the pre-processed method and then see the method of reading three data. The main function of the executenonquery () method is to return the affected row. It has two overloads, and all of the overload methods of all ExecuteNonQuery are listed below. ExecutenonQuery method public Static int ExecutenonQuery String Connstring, CommandType cmdtype, String cmdtext, Params Sqlparameter [] cmdparms) {SqlCommand cmd = new SqlCommand (); using (SqlConnection conn = new SqlConnection (connString)) {PrepareCommand (cmd, conn, null, cmdType, cmdText, cmdParms); int val = cmd.ExecuteNonQuery (); cmd.Parameters.Clear (); Return val;}} The parameter is in turn: Database connection string, execute command type, SQL statement, and an array of SQL parameters. After that means indicates that the database operation is complete, the database connection is automatically turned off and releases system resources. ExecutenonQuery method (overload one) public Static int ExecutenonQuery (SqlConnection CONN, CommandType CmdType, String cmdtext, Params Sqlparameter [] cmdparms) ExecutenonQuery method (overloaded) public Static int ExecutenonQuery (SqlTransaction Trans, CommandType CmdType, String cmdtext, Params Sqlparameter [] cmdparms) ExecuteReader method public Static SqlDataReader ExecuteReader String Connstring, CommandType cmdtype, String cmdtext, Params Sqlparameter [] cmdparms) {SqlCommand cmd = new SqlCommand (); SqlConnection conn = new SqlConnection (connString); // we use a try / catch here because if the method throws an exception we want to // close the connection throw code, because no datareader will exist , hence the // commandBehaviour.CloseConnection will not work try {PrepareCommand (cmd, conn, null, cmdType, cmdText, cmdParms); SqlDataReader rdr = cmd.ExecuteReader (CommandBehavior.CloseConnection); cmd.Parameters.Clear (); return rdr ;} Catch {conn.close (); throw;}} ExecuteReader contains four parameters: database connection string, database execution type, SQL statement, and an array of SQL parameter. The main role is to provide a way to read only the travel stream from the database. Finally there is an ExecuteScalar method. This provides an overload. Its main purpose is to return to the number of rows that affect database records. public Static Object Executescalar String Connstring, CommandType cmdtype, String cmdtext, Params Sqlparameter [] cmdparms) ExecuteScalar overload public Static Object ExecuteScalar (SqlConnection CONN, CommandType Cmdtype, String cmdtext, Params Sqlparameter [] cmdparms) PETSHOP's SQLHELPER.CS is basically finished. In the back call, you will also return to learn SQLHELPER.CS. First flash ...
