BAEL-1419: Guide to cockroachDB in Java (#3325)

* adding CockroachDB code

* Fixed database name

* Added handling transaction examples

persistence-modules/java-cockroachdb/src/main/java/com/baeldung/cockroachdb/domain/Article.java

@@ -0,0 +1,43 @@
+package com.baeldung.cockroachdb.domain;
+
+import java.util.UUID;
+
+public class Article {
+
+    private UUID id;
+
+    private String title;
+
+    private String author;
+
+    public Article(UUID id, String title, String author) {
+        this.id = id;
+        this.title = title;
+        this.author = author;
+    }
+
+    public UUID getId() {
+        return id;
+    }
+
+    public void setId(UUID id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+}

persistence-modules/java-cockroachdb/src/main/java/com/baeldung/cockroachdb/repository/ArticleRepository.java

@@ -0,0 +1,172 @@
+package com.baeldung.cockroachdb.repository;
+
+import com.baeldung.cockroachdb.domain.Article;
+
+import java.sql.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * Repository for the articles table related operations
+ */
+public class ArticleRepository {
+
+    private static final String TABLE_NAME = "articles";
+    private Connection connection;
+
+    public ArticleRepository(Connection connection) {
+        this.connection = connection;
+    }
+
+    /**
+     * Creates the articles table.
+     */
+    public void createTable() throws SQLException {
+        StringBuilder sb = new StringBuilder("CREATE TABLE IF NOT EXISTS ").append(TABLE_NAME)
+          .append("(id uuid PRIMARY KEY, ")
+          .append("title string,")
+          .append("author string)");
+
+        final String query = sb.toString();
+        Statement stmt = connection.createStatement();
+        stmt.execute(query);
+    }
+
+    /**
+     * Alter the articles table adding a column
+     *
+     * @param columnName Column name of the additional column
+     * @param columnType Column type of the additional column
+     * @throws SQLException
+     */
+    public void alterTable(String columnName, String columnType) throws SQLException {
+        StringBuilder sb = new StringBuilder("ALTER TABLE ").append(TABLE_NAME)
+          .append(" ADD ")
+          .append(columnName)
+          .append(" ")
+          .append(columnType);
+
+        final String query = sb.toString();
+        Statement stmt = connection.createStatement();
+        stmt.execute(query);
+    }
+
+    /**
+     * Insert a new article in the articles table
+     *
+     * @param article New article to insert
+     * @throws SQLException
+     */
+    public void insertArticle(Article article) throws SQLException {
+        StringBuilder sb = new StringBuilder("INSERT INTO ").append(TABLE_NAME)
+          .append("(id, title, author) ")
+          .append("VALUES (?,?,?)");
+
+        final String query = sb.toString();
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setString(1, article.getId().toString());
+        preparedStatement.setString(2, article.getTitle());
+        preparedStatement.setString(3, article.getAuthor());
+        preparedStatement.execute();
+    }
+
+    /**
+     * Select article by Title
+     *
+     * @param title title of the article to retrieve
+     * @return article with the given title
+     * @throws SQLException
+     */
+    public Article selectByTitle(String title) throws SQLException {
+        StringBuilder sb = new StringBuilder("SELECT * FROM ").append(TABLE_NAME)
+          .append(" WHERE title = ?");
+
+        final String query = sb.toString();
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setString(1, title);
+
+        try (ResultSet rs = preparedStatement.executeQuery()) {
+
+            List<Article> articles = new ArrayList<>();
+
+            while (rs.next()) {
+                Article article = new Article(
+                    UUID.fromString(rs.getString("id")), 
+                    rs.getString("title"), 
+                    rs.getString("author")
+                    );
+                articles.add(article);
+            }
+            return articles.get(0);
+        }
+
+    }
+
+    /**
+     * Select all the articles
+     *
+     * @return list of all articles
+     * @throws SQLException
+     */
+    public List<Article> selectAll() throws SQLException {
+        StringBuilder sb = new StringBuilder("SELECT * FROM ").append(TABLE_NAME);
+
+        final String query = sb.toString();
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        try (ResultSet rs = preparedStatement.executeQuery()) {
+
+            List<Article> articles = new ArrayList<>();
+
+            while (rs.next()) {
+                Article article = new Article(
+                  UUID.fromString(rs.getString("id")), 
+                  rs.getString("title"), 
+                  rs.getString("author")
+                  );
+                articles.add(article);
+            }
+            return articles;
+        }
+    }
+
+    /**
+     * Delete article by title
+     *
+     * @param title title of the article to delete
+     * @throws SQLException
+     */
+    public void deleteArticleByTitle(String title) throws SQLException {
+        StringBuilder sb = new StringBuilder("DELETE FROM ").append(TABLE_NAME)
+          .append(" WHERE title = ?");
+
+        final String query = sb.toString();
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setString(1, title);
+        preparedStatement.execute();
+    }
+
+    /**
+     * Delete all rows in the table
+     *
+     * @throws SQLException
+     */
+    public void truncateTable() throws SQLException {
+        StringBuilder sb = new StringBuilder("TRUNCATE TABLE ").append(TABLE_NAME);
+
+        final String query = sb.toString();
+        Statement stmt = connection.createStatement();
+        stmt.execute(query);
+    }
+
+    /**
+     * Delete table
+     */
+    public void deleteTable() throws SQLException {
+        StringBuilder sb = new StringBuilder("DROP TABLE IF EXISTS ").append(TABLE_NAME);
+
+        final String query = sb.toString();
+        Statement stmt = connection.createStatement();
+        stmt.execute(query);
+    }
+}