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new 4df73267 Add documentation to limit rows from JDBC ResultSets
4df73267 is described below
commit 4df73267ce7680d829ad3edffadcfbbf94c25e43
Author: Gary Gregory <garydgreg...@gmail.com>
AuthorDate: Thu Mar 13 01:59:24 2025 -0400
Add documentation to limit rows from JDBC ResultSets
---
src/main/javadoc/overview.html | 51 ++++++++++++++++++++++++++++++++++--------
1 file changed, 42 insertions(+), 9 deletions(-)
diff --git a/src/main/javadoc/overview.html b/src/main/javadoc/overview.html
index 59155833..0598cf19 100644
--- a/src/main/javadoc/overview.html
+++ b/src/main/javadoc/overview.html
@@ -314,15 +314,15 @@ try (ResultSet resultSet = ...) {
</pre>
</section>
<section>
- <h1>Exporting JDBC Result Sets</h1>
- <p>
- To export row data from a JDBC
- <code>ResultSet</code>
- , use
- <code>CSVPrinter.printRecords(ResultSet)</code>
- :
- </p>
- <pre>
+ <h1>Working with JDBC</h1>
+ <section>
+ <h2>Exporting JDBC Result Sets</h2>
+ <p>
+ To export row data from a JDBC
+ <code>ResultSet</code>
+ , use <a
href="org/apache/commons/csv/CSVPrinter.html#printRecords(java.sql.ResultSet)">CSVPrinter.printRecords(ResultSet)</a>
:
+ </p>
+ <pre>
<code>
final StringWriter sw = new StringWriter();
final CSVFormat csvFormat = CSVFormat.DEFAULT;
@@ -337,6 +337,39 @@ try (ResultSet resultSet = ...) {
System.out.println(csv);
</code>
</pre>
+ </section>
+ <section>
+ <h2>Limiting rows from JDBC Result Sets</h2>
+ <p>SQL lets you limit how many rows a SELECT statement returns with the
LIMIT clause.</p>
+ <p>
+ When you can't or don't want to change the SQL used to generate rows,
JDBC lets you limit how many rows a JDBC Statement returns with the <a
+
href="https://docs.oracle.com/en/java/javase/21/docs/api/java.sql/java/sql/Statement.html#setMaxRows(int)">Statement.setMaxRows(int)</a>
method.
+ </p>
+ <p>
+ When you get a JDBC ResultSet from an API like <a
+
href="https://docs.oracle.com/en/java/javase/21/docs/api/java.sql/java/sql/DatabaseMetaData.html#getProcedures(java.lang.String,java.lang.String,java.lang.String)">
+ DatabaseMetaData.getProcedures(...)</a>, there is no SQL or JDBC
Statement to use to set a limit, the ResultSet class does not have an API to
limit rows.
+ </p>
+ <p>
+ To simplify limiting ResultSet rows, Commons CVS offers the <a
href="org/apache/commons/csv/CSVFormat.Builder.html#setMaxRows(long)">CSVFormat.Builder.setMaxRows(long)</a>
+ method. For example:
+ </p>
+ <pre>
+ <code>
+ CSVFormat csvFormat = CSVFormat.DEFAULT
+ .setMaxRows(5_000)
+ .get();
+ try (ResultSet resultSet = ...) {
+ csvFormat.printer().printRecords(resultSet);
+ }
+ </code>
+ </pre>
+ <p>
+ Using the above, calling <a
href="org/apache/commons/csv/CSVPrinter.html#printRecords(java.sql.ResultSet)">CSVPrinter.printRecords(ResultSet)</a>
will
+ limit the row count to the maximum number of rows specified in
setMaxRows().
+ </p>
+ <p>Note that setMaxRows() works with the other methods that print a
sequence of records.</p>
+ </section>
</section>
</body>
</html>
