Add a static method to more easily construct an SqlColumn

- Fixes #2

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/SqlColumn.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2017 the original author or authors.
+ *    Copyright 2016-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -96,10 +96,23 @@ public String renderWithTableAlias(TableAliasCalculator tableAliasCalculator) {
                 .orElseGet(this::name);
     }
 
+    public <S> SqlColumn<S> withTypeHandler(String typeHandler) {
+        SqlColumn<S> column = new SqlColumn<>(this);
+        column.typeHandler = Optional.of(typeHandler);
+        return column;
+    }
+
     private String applyTableAlias(String tableAlias) {
         return tableAlias + "." + name(); //$NON-NLS-1$
     }
 
+    public static <T> SqlColumn<T> of(String name, SqlTable table, JDBCType jdbcType) {
+        return SqlColumn.withName(name)
+                .withTable(table)
+                .withJdbcType(jdbcType)
+                .build();
+    }
+    
     public static Builder withName(String name) {
         return new Builder().withName(name);
     }

src/main/java/org/mybatis/dynamic/sql/SqlTable.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2017 the original author or authors.
+ *    Copyright 2016-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -31,18 +31,11 @@ public String name() {
     }
 
     public <T> SqlColumn<T> column(String name, JDBCType jdbcType) {
-        return SqlColumn.withName(name)
-                .withJdbcType(jdbcType)
-                .withTable(this)
-                .build();
+        return SqlColumn.of(name, this, jdbcType);
     }
 
     public <T> SqlColumn<T> column(String name, JDBCType jdbcType, String typeHandler) {
-        return SqlColumn.withName(name)
-                .withJdbcType(jdbcType)
-                .withTypeHandler(typeHandler)
-                .withTable(this)
-                .build();
+        return SqlColumn.of(name, this, jdbcType).withTypeHandler(typeHandler);
     }
 
     public static SqlTable of(String name) {

src/test/java/org/mybatis/dynamic/sql/mybatis3/CriterionRendererTest.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2017 the original author or authors.
+ *    Copyright 2016-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -130,7 +130,11 @@ public void testNoAliasWithoutIgnore() {
     @Test
     public void testTypeHandler() {
         SqlTable table = SqlTable.of("foo");
-        SqlColumn<Date> column = table.column("id", JDBCType.DATE, "foo.Bar");
+        SqlColumn<Date> column = SqlColumn.withName("id")
+                .withTable(table)
+                .withJdbcType(JDBCType.DATE)
+                .withTypeHandler("foo.Bar")
+                .build();
         IsEqualTo<Date> condition = IsEqualTo.of(() -> new Date());
         SqlCriterion<Date> criterion = SqlCriterion.withColumn(column)
                 .withCondition(condition)