show tables works

weed/command/sql.go

@@ -92,6 +92,11 @@ func runSql(command *Command, args []string) bool {
 		interactive:     interactive,
 	}
 
+	// Set current database in SQL engine if specified via command line
+	if *sqlDatabase != "" {
+		ctx.engine.GetCatalog().SetCurrentDatabase(*sqlDatabase)
+	}
+
 	// Execute based on mode
 	switch {
 	case *sqlQuery != "":
@@ -215,12 +220,19 @@ func runInteractiveShell(ctx *SQLContext) bool {
 		}
 
 		// Handle database switching
-		if strings.HasPrefix(strings.ToUpper(line), "USE ") {
-			dbName := strings.TrimSpace(strings.TrimPrefix(strings.ToUpper(line), "USE "))
-			dbName = strings.TrimSuffix(dbName, ";")
-			ctx.currentDatabase = dbName
-			fmt.Printf("Database changed to: %s\n\n", dbName)
-			continue
+		upperLine := strings.ToUpper(line)
+		if strings.HasPrefix(upperLine, "USE ") {
+			// Extract database name preserving original case
+			parts := strings.SplitN(line, " ", 2)
+			if len(parts) >= 2 {
+				dbName := strings.TrimSpace(parts[1])
+				dbName = strings.TrimSuffix(dbName, ";")
+				ctx.currentDatabase = dbName
+				// Also update the SQL engine's catalog current database
+				ctx.engine.GetCatalog().SetCurrentDatabase(dbName)
+				fmt.Printf("Database changed to: %s\n\n", strings.ToUpper(dbName))
+				continue
+			}
 		}
 
 		// Handle output format switching

weed/query/engine/describe.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"fmt"
 	"strings"
-	
+
 	"github.com/seaweedfs/seaweedfs/weed/query/sqltypes"
 	"github.com/xwb1989/sqlparser"
 )
@@ -18,32 +18,32 @@ func (e *SQLEngine) executeDescribeStatement(ctx context.Context, tableName stri
 			database = "default"
 		}
 	}
-	
+
 	// Get topic schema from broker
 	recordType, err := e.catalog.brokerClient.GetTopicSchema(ctx, database, tableName)
 	if err != nil {
 		return &QueryResult{Error: err}, err
 	}
-	
+
 	// Format schema as DESCRIBE output
 	result := &QueryResult{
 		Columns: []string{"Field", "Type", "Null", "Key", "Default", "Extra"},
 		Rows:    make([][]sqltypes.Value, len(recordType.Fields)),
 	}
-	
+
 	for i, field := range recordType.Fields {
 		sqlType := e.convertMQTypeToSQL(field.Type)
-		
+
 		result.Rows[i] = []sqltypes.Value{
-			sqltypes.NewVarChar(field.Name),           // Field
-			sqltypes.NewVarChar(sqlType),              // Type
-			sqltypes.NewVarChar("YES"),                // Null (assume nullable)
-			sqltypes.NewVarChar(""),                   // Key (no keys for now)
-			sqltypes.NewVarChar("NULL"),               // Default
-			sqltypes.NewVarChar(""),                   // Extra
+			sqltypes.NewVarChar(field.Name), // Field
+			sqltypes.NewVarChar(sqlType),    // Type
+			sqltypes.NewVarChar("YES"),      // Null (assume nullable)
+			sqltypes.NewVarChar(""),         // Key (no keys for now)
+			sqltypes.NewVarChar("NULL"),     // Default
+			sqltypes.NewVarChar(""),         // Extra
 		}
 	}
-	
+
 	return result, nil
 }
 
@@ -53,8 +53,16 @@ func (e *SQLEngine) executeShowStatementWithDescribe(ctx context.Context, stmt *
 	case "DATABASES":
 		return e.showDatabases(ctx)
 	case "TABLES":
-		// TODO: Parse FROM clause properly for database specification
-		return e.showTables(ctx, "")
+		// Parse FROM clause for database specification, or use current database context
+		database := ""
+		if stmt.OnTable.Name.String() != "" {
+			// SHOW TABLES FROM database_name
+			database = stmt.OnTable.Name.String()
+		} else {
+			// Use current database context
+			database = e.catalog.GetCurrentDatabase()
+		}
+		return e.showTables(ctx, database)
 	case "COLUMNS":
 		// SHOW COLUMNS FROM table is equivalent to DESCRIBE
 		if stmt.OnTable.Name.String() != "" {
@@ -82,16 +90,16 @@ func (e *SQLEngine) handleDescribeCommand(ctx context.Context, sql string) (*Que
 		err := fmt.Errorf("DESCRIBE requires a table name")
 		return &QueryResult{Error: err}, err
 	}
-	
+
 	tableName := parts[1]
 	database := ""
-	
+
 	// Handle database.table format
 	if strings.Contains(tableName, ".") {
 		parts := strings.SplitN(tableName, ".", 2)
 		database = parts[0]
 		tableName = parts[1]
 	}
-	
+
 	return e.executeDescribeStatement(ctx, tableName, database)
 }

weed/query/engine/engine.go

@@ -41,6 +41,11 @@ func NewSQLEngine(masterAddress string) *SQLEngine {
 	}
 }
 
+// GetCatalog returns the schema catalog for external access
+func (e *SQLEngine) GetCatalog() *SchemaCatalog {
+	return e.catalog
+}
+
 // ExecuteSQL parses and executes a SQL statement
 // Assumptions:
 // 1. All SQL statements are MySQL-compatible via xwb1989/sqlparser
@@ -823,11 +828,12 @@ func (e *SQLEngine) showDatabases(ctx context.Context) (*QueryResult, error) {
 }
 
 func (e *SQLEngine) showTables(ctx context.Context, dbName string) (*QueryResult, error) {
-	// Assumption: If no database specified, use default or return error
+	// Use current database context if no database specified
 	if dbName == "" {
-		// TODO: Implement default database context
-		// For now, use 'default' as the default database
-		dbName = "default"
+		dbName = e.catalog.GetCurrentDatabase()
+		if dbName == "" {
+			dbName = "default"
+		}
 	}
 
 	tables, err := e.catalog.ListTables(dbName)