update comment

ktorm-support-postgresql/src/main/kotlin/org/ktorm/support/postgresql/Global.kt

@@ -68,6 +68,31 @@ internal val Database.Companion.global: Database get() {
  * on conflict (id) do update set salary = salary + ?
  * ```
  *
+ * By default, the column used in the `on conflict` statement is the primary key you already defined in
+ * the schema definition. If you want, you can specify one or more columns for the `on conflict` statement
+ * as belows:
+ *
+ * ```kotlin
+ * Employees.insertOrUpdate {
+ *     set(it.id, 1)
+ *     set(it.name, "vince")
+ *     set(it.job, "engineer")
+ *     set(it.salary, 1000)
+ *     set(it.hireDate, LocalDate.now())
+ *     set(it.departmentId, 1)
+ *     onConflict(it.name, it.job) {
+ *         set(it.salary, it.salary + 900)
+ *     }
+ * }
+ * ```
+ *
+ * Generated SQL:
+ *
+ * ```sql
+ * insert into t_employee (id, name, job, salary, hire_date, department_id) values (?, ?, ?, ?, ?, ?)
+ * on conflict (name, job) do update set salary = salary + ?
+ * ```
+ *
  * @param block the DSL block used to construct the expression.
  * @return the effected row count.
  */
@@ -157,6 +182,42 @@ public fun <T : BaseTable<*>> T.bulkInsert(block: BulkInsertStatementBuilder<T>.
  * on conflict (id) do update set salary = salary + ?
  * ```
  *
+ * By default, the column used in the `on conflict` statement is the primary key you already defined in
+ * the schema definition. If you want, you can specify one or more columns for the `on conflict` statement
+ * as belows:
+ *
+ * ```kotlin
+ * Employees.bulkInsertOrUpdate {
+ *     item {
+ *         set(it.id, 1)
+ *         set(it.name, "vince")
+ *         set(it.job, "engineer")
+ *         set(it.salary, 1000)
+ *         set(it.hireDate, LocalDate.now())
+ *         set(it.departmentId, 1)
+ *     }
+ *     item {
+ *         set(it.id, 5)
+ *         set(it.name, "vince")
+ *         set(it.job, "engineer")
+ *         set(it.salary, 1000)
+ *         set(it.hireDate, LocalDate.now())
+ *         set(it.departmentId, 1)
+ *     }
+ *     onConflict(it.name, it.job) {
+ *         set(it.salary, it.salary + 900)
+ *     }
+ * }
+ * ```
+ *
+ * Generated SQL:
+ *
+ * ```sql
+ * insert into t_employee (id, name, job, salary, hire_date, department_id)
+ * values (?, ?, ?, ?, ?, ?), (?, ?, ?, ?, ?, ?)
+ * on conflict (name, job) do update set salary = salary + ?
+ * ```
+ *
  * @since 3.3.0
  * @param block the DSL block used to construct the expression.
  * @return the effected row count.