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SQLJ is a working title for efforts to combine Java and SQL. It was a common effort started around 1997 by engineers from IBM, Oracle, Compaq, Informix, Sybase, Cloudscape and Sun Microsystems.
It consists of the three parts: 0, 1 and 2. Part 0 describes the embedding of SQL statements into Java programs. SQLJ part 0 is the basis for part 10 of the SQL:1999 standard, aka SQL Object Language Bindings (SQL/OLB).[1] SQLJ parts 1 and 2 describes the converse possibility to use Java classes (routines and types) from SQL statements. Parts 1 and 2 are the basis for part 13 of the SQL standard, SQL Routines and Types Using the Java Programming Language (SQL/JRT).
"SQLJ" is commonly used to refer to just SQLJ part 0, usually when it is contrasted with other means of embedding SQL in Java, like JDBC.
Part 0 was updated for JDBC 2.0 compatibility and ratified by ISO in 2000. The last two parts were combined when submitted to ISO. Part 2 was substantially rewritten for the ISO submission because the ANSI version was not formal enough for a specification, being closer to the style of a user manual. The combined version was ratified in 2002.[1]
The SQLJ part 0 specification largely originated from Oracle, who also provided the first reference implementation.[1]
In the following SQLJ is a synonym for SQLJ part 0.
Whereas JDBC provides an API, SQLJ consists of a language extension. Thus programs containing SQLJ must be run through a preprocessor (the SQLJ translator) before they can be compiled.
Some advantages of SQLJ over JDBC include:
The following examples compare SQLJ syntax with JDBC usage.
| JDBC | SQLJ |
|---|---|
PreparedStatement stmt = conn.prepareStatement(
"SELECT LASTNAME"
+ " , FIRSTNME"
+ " , SALARY"
+ " FROM DSN8710.EMP"
+ " WHERE SALARY BETWEEN ? AND ?");
stmt.setBigDecimal(1, min);
stmt.setBigDecimal(2, max);
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
lastname = rs.getString(1);
firstname = rs.getString(2);
salary = rs.getBigDecimal(3);
// Print row...
}
rs.close();
stmt.close();
|
#sql private static iterator EmployeeIterator(String, String, BigDecimal);
...
EmployeeIterator iter;
#sql [ctx] iter = {
SELECT LASTNAME
, FIRSTNME
, SALARY
FROM DSN8710.EMP
WHERE SALARY BETWEEN :min AND :max
};
do {
#sql {
FETCH :iter
INTO :lastname, :firstname, :salary
};
// Print row...
} while (!iter.endFetch());
iter.close();
|
| JDBC | SQLJ |
|---|---|
PreparedStatement stmt = conn.prepareStatement(
"SELECT MAX(SALARY), AVG(SALARY)"
+ " FROM DSN8710.EMP");
rs = stmt.executeQuery();
if (!rs.next()) {
// Error—no rows found
}
maxSalary = rs.getBigDecimal(1);
avgSalary = rs.getBigDecimal(2);
if (rs.next()) {
// Error—more than one row found
}
rs.close();
stmt.close();
|
#sql [ctx] {
SELECT MAX(SALARY), AVG(SALARY)
INTO :maxSalary, :avgSalary
FROM DSN8710.EMP
};
|
| JDBC | SQLJ |
|---|---|
stmt = conn.prepareStatement(
"INSERT INTO DSN8710.EMP " +
"(EMPNO, FIRSTNME, MIDINIT, LASTNAME, HIREDATE, SALARY) "
+ "VALUES (?, ?, ?, ?, CURRENT DATE, ?)");
stmt.setString(1, empno);
stmt.setString(2, firstname);
stmt.setString(3, midinit);
stmt.setString(4, lastname);
stmt.setBigDecimal(5, salary);
stmt.executeUpdate();
stmt.close();
|
#sql [ctx] {
INSERT INTO DSN8710.EMP
(EMPNO, FIRSTNME, MIDINIT, LASTNAME, HIREDATE, SALARY)
VALUES
(:empno, :firstname, :midinit, :lastname, CURRENT DATE, :salary)
};
|
By: Wikipedia.org
Edited: 2021-06-19 12:42:30
Source: Wikipedia.org
