Fix bug show full column does not display default value

Signed-off-by: Astralidea <astralidea@163.com>

fe/fe-core/src/main/java/com/starrocks/catalog/Column.java

@@ -523,6 +523,9 @@ public String getMetaDefaultValue(List<String> extras) {
             if ("now()".equalsIgnoreCase(defaultExpr.getExpr())) {
                 extras.add("DEFAULT_GENERATED");
                 return "CURRENT_TIMESTAMP";
+            } else {
+                extras.add("DEFAULT_GENERATED");
+                return defaultExpr.getExpr();
             }
         }
         return FeConstants.null_string;

fe/fe-core/src/test/java/com/starrocks/analysis/ShowColumnStmtTest.java

@@ -0,0 +1,65 @@
+package com.starrocks.analysis;
+
+import com.starrocks.common.Config;
+import com.starrocks.common.FeConstants;
+import com.starrocks.qe.ConnectContext;
+import com.starrocks.qe.ShowExecutor;
+import com.starrocks.qe.ShowResultSet;
+import com.starrocks.server.GlobalStateMgr;
+import com.starrocks.sql.ast.DropTableStmt;
+import com.starrocks.sql.ast.ShowColumnStmt;
+import com.starrocks.utframe.StarRocksAssert;
+import com.starrocks.utframe.UtFrameUtils;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class ShowColumnStmtTest {
+
+    private static ConnectContext connectContext;
+    private static StarRocksAssert starRocksAssert;
+
+    @BeforeClass
+    public static void beforeClass() throws Exception {
+        FeConstants.runningUnitTest = true;
+        Config.dynamic_partition_enable = true;
+        Config.dynamic_partition_check_interval_seconds = 1;
+        Config.enable_strict_storage_medium_check = false;
+        UtFrameUtils.createMinStarRocksCluster();
+        UtFrameUtils.addMockBackend(10002);
+        UtFrameUtils.addMockBackend(10003);
+        // create connect context
+        connectContext = UtFrameUtils.createDefaultCtx();
+        starRocksAssert = new StarRocksAssert(connectContext);
+
+        starRocksAssert.withDatabase("test").useDatabase("test")
+                .withTable("create table test_default\n" +
+                        "(id varchar(255) default (uuid()))\n" +
+                        "distributed by hash(id)\n" +
+                        "PROPERTIES ( \"replication_num\" = \"1\" )");
+    }
+
+    @AfterClass
+    public static void tearDown() throws Exception {
+        ConnectContext ctx = starRocksAssert.getCtx();
+        String dropSQL = "drop table test_default";
+        try {
+            DropTableStmt dropTableStmt = (DropTableStmt) UtFrameUtils.parseStmtWithNewParser(dropSQL, ctx);
+            GlobalStateMgr.getCurrentState().dropTable(dropTableStmt);
+        } catch (Exception ex) {
+
+        }
+    }
+
+    @Test
+    public void testShowDefaultValue() throws Exception {
+        ConnectContext ctx = starRocksAssert.getCtx();
+        String sql = "show full columns from test_default;";
+        ShowColumnStmt showColumnStmt = (ShowColumnStmt) UtFrameUtils.parseStmtWithNewParser(sql, ctx);
+        ShowExecutor executor = new ShowExecutor(ctx, showColumnStmt);
+        ShowResultSet resultSet = executor.execute();
+        Assert.assertEquals("uuid()", resultSet.getResultRows().get(0).get(5));
+    }
+
+}