Open SQL Examples
This section provides several Open SQL examples.
An Open SQL Insert Example
This example shows how to use the Open SQL class
RWDBOSql in an Oracle insert operation. The insert is done on a
foo table with an
int column and a
float column.
const size_t NUMBER_OF_ROWS = 10;
RWDBOSql openSql;
RWDBTBuffer<int> intBuffer(NUMBER_OF_ROWS); //1
RWDBTBuffer<float> floatBuffer(NUMBER_OF_ROWS); //2
RWCString oracleSyntaxSql("INSERT INTO foo VALUES(:c1, :c2)"); //3
openSql.statement(oracleSyntaxSql); //4
openSql << intBuffer; //5
openSql << floatBuffer; //6
while (FillupValues(intBuffer, floatBuffer, NUMBER_OF_ROWS)){ //7
openSql.execute(conn); //8
if (!openSql.isValid()) { //9
cout << "Insert Into foo Has Failed" << endl;
break;
}
}
Open SQL Query Examples
These examples illustrate how an
RWDBOSql object can be used to execute a
SELECT query and retrieve its results. The
SELECT query is executed on an employee table
emp and retrieves all columns of the table for employees in a particular department. The example assumes an error handler is associated with the connection in use, and doesn't check for any errors after calls to the
RWDBOSql object.
The structure of the table emp is:
empno INT NOT NULL
ename VARCHAR(10) NOT NULL
posn VARCHAR(9) NOT NULL
mgr INT NULL
sal NUMERIC(7,2) NOT NULL
dept INT NOT NULL
The first example assumes awareness of the structure of table emp, and hence the schema of the result set returned by the query.
RWDBOSql openSql("SELECT * FROM emp WHERE dept = :dept", RWDBOSql::Query); //1
RWDBTBuffer<int> queryDeptBuff; //2
queryDeptBuff[0] = 3; //3
openSql << queryDeptBuff; //4
openSql.execute(cn); //5
const size_t ROWS_TO_FETCH = 5; //6
RWDBTBuffer<int> empnoBuff(ROWS_TO_FETCH), mgrBuff(ROWS_TO_FETCH),
deptBuff(ROWS_TO_FETCH);
RWDBTBuffer<RWCString> enameBuff(ROWS_TO_FETCH), posnBuff(ROWS_TO_FETCH);
RWDBTBuffer<RWDecimalPortable> salBuff(ROWS_TO_FETCH); //7
openSql[0] >> empnoBuff >> enameBuff >> posnBuff >>
mgrBuff >> salBuff >> deptBuff; //8
long rowsFetched = 0;
while ((rowsFetched = openSql.fetch().rowsFetched()) > 0) { //9
for (size_t i = 0; i < rowsFetched; ++i) {
cout << empnoBuff[i] << "\t" << enameBuff[i] << "\t"
<< posnBuff[i] << "\t"; //10
if (mgrBuff.isNull(i)) { //11
cout << "NULL";
}
else {
cout << mgrBuff[i];
}
cout << "\t" << salBuff[i] << "\t" << deptBuff[i] << endl;
}
}
The second example assumes execution of an ad hoc query for which the schema of the result set is not known beforehand.
RWDBOSql openSql("SELECT * FROM emp WHERE dept = :dept", RWDBOSql::Query);
RWDBTBuffer<int> queryDeptBuff;
queryDeptBuff[0] = 3;
openSql << queryDeptBuff;
openSql.execute(cn);
const size_t ROWS_TO_FETCH = 5;
RWDBMultiRow mRow(openSql.schema(), ROWS_TO_FETCH); //1
openSql[0] = mRow; //2
long rowsFetched = 0;
while ((rowsFetched = openSql.fetch().rowsFetched()) > 0) { //3
for (size_t row = 0; row < rowsFetched; ++row) {
for (size_t col = 0; col < mRow.numberOfColumns(); ++col) { //4
RWDBValue val = mRow[row][col]; //5
if ( val.isNull() ) { //6
cout << "NULL" << "\t";
}
else {
cout << val.asString() << "\t";
}
}
cout << endl;
}
}
The steps until
RWDBOSql execution are the same as in the previous example.
An Open SQL Stored Procedure Example
This example illustrates how to execute a stored procedure using an
RWDBOSql object. The stored procedure used here is assumed to take one input-output parameter of type
int. It returns two result sets: the first consists of character strings; the second of two columns of types
int and
RWDecimalPortable. The example assumes an error handler is associated with the connection in use, and doesn't check for any errors after calls to the
RWDBOSql object.
const size_t NUMBER_OF_ROWS = 10;
RWDBTBuffer<int> index; //1
index.paramType(RWDBColumn::inOutParameter); //2
index[0] = 100; //3
RWDBTBuffer<RWDBNativeType1> cursor1, cursor2; //4
RWDBTBuffer<RWCString> result1 (NUMBER_OF_ROWS); //5
RWDBTBuffer<int> result2_1 (NUMBER_OF_ROWS); //6
RWDBTBuffer<RWDecimalPortable> result2_2 (NUMBER_OF_ROWS); //7
RWDBOSql openSql ("BEGIN myProc (:index, :cursor1, :cursor2); END;",
RWDBOSql::Procedure); //8
openSql << index << cursor1 << cursor2; //9
openSql[0] >> result1; //10
openSql[1] >> result2_1 >> result2_2; //11
openSql.execute(conn); //12
long count = 0;
while ((count = openSql.fetch().rowsFetched()) > 0 ) { //13
for (int row = 0; row < count; row++) {
cout << "STRING VALUE :" << result1[row] << endl;
}
}
while ((count = openSql.fetch().rowsFetched()) > 0 ) { //14
for (int row = 0; row < count; row++) {
cout << "INT VALUE :" << result2_1[row] << endl;
cout << "DECIMAL VALUE: " << result2_2[row] << endl;
}
}
openSql.fetchReturnParams(); //15
cout << "OUT PARAM :" << index[0] << endl; //16
OCIStmts
Each
RWDBOSql object corresponds to an Oracle OCI
OCIStmt structure. An
OCIStmt structure is created and associated with an
RWDBOSql object only when the
execute() method is invoked on the
RWDBOSql object. The
OCIStmt structure remains associated until the
RWDBOSql object goes out of scope, or an
execute() is invoked on the object using a different connection. Invoking
execute() on the same connection reuses the same
OCIStmt structure.
Simultaneous Processing of Results on an RWDBOSql Object When Used for Stored Procedure
Multiple result sets produced by a stored procedure execution are handled through additional OCIStmts. To simplify usage, Open SQL does not support simultaneous fetching of multiple result sets. You must complete the current result set, by fetching all the data or canceling, in order to move on to the next result set.