Java Reference
In-Depth Information
•The
WHERE
and
ORDER
BY
clauses can be combined in one query. If used,
ORDER BY
must be the
last clause in the query.
Section 24.4.4 Merging Data from Multiple Tables:
INNER JOIN
•An
INNER
JOIN
(p. 1057) merges rows from two tables by matching values in columns that are
common to the tables. The basic form for the
INNER
JOIN
operator is:
SELECT
columnName1
,
columnName2
, …
FROM
table1
INNER JOIN
table2
ON
table1
.
columnName
=
table2
.
columnName
The
ON
clause (p. 1057) specifies the columns from each table that are compared to determine
which rows are joined. If a SQL statement uses columns with the same name from multiple ta-
bles, the column names must be fully qualified (p. 1057) by prefixing them with their table
names and a dot (
.
).
Section 24.4.5
INSERT
Statement
•An
INSERT
statement (p. 1058) inserts a new row into a table. The basic form of this statement is
INSERT INTO
tableName
(
columnName1
,
columnName2
,
…
,
columnNameN
)
VALUES
(
value1
,
value2
,
…
,
valueN
)
where
tableName
is the table in which to insert the row. The
tableName
is followed by a comma-
separated list of column names in parentheses. The list of column names is followed by the SQL
keyword
VALUES
(p. 1058) and a comma-separated list of values in parentheses.
• SQL uses single quotes (
'
) to delimit strings. To specify a string containing a single quote in
SQL, escape the single quote with another single quote (i.e.,
''
).
Section 24.4.6
UPDATE
Statement
•An
UPDATE
statement (p. 1059) modifies data in a table. The basic form of an
UPDATE
statement is
UPDATE
tableName
SET
columnName1
=
value1
,
columnName2
=
value2
,
…
,
columnNameN
=
valueN
WHERE
criteria
where
tableName
is the table to update. Keyword
SET
(p. 1059) is followed by a comma-separated
list of
columnName
=
value
pairs. The optional
WHERE
clause determines which rows to update.
Section 24.4.7
DELETE
Statement
•A
DELETE
statement (p. 1060) removes rows from a table. The simplest form for a
DELETE
state-
ment is
DELETE FROM
tableName
WHERE
criteria
where
tableName
is the table from which to delete a row (or rows). The optional
WHERE
criteria
determines which rows to delete. If this clause is omitted, all the table's rows are deleted.
Section 24.5 Setting up a Java DB Database
• Oracle's pure Java database Java DB (p. 1060) is installed with the JDK on Windows, Mac OS
X and Linux.
• Java DB has both an embedded version and a network version.
• The Java DB software is located in the
db
subdirectory of your JDK's installation directory.
• Java DB comes with several files that enable you to configure and run it. Before executing these
files from a command window, you must set the environment variable
JAVA_HOME
to refer to the
JDK's exact installation directory.
