add virtual db

README.md

@@ -1 +1,18 @@
-# sql-calculator
+# sql-calculator
+
+## virtual db
+模拟数据库的 ddl 执行得到数据库结构
+```go
+vb := NewVirtualDB("")
+vb.ExecSQL("create database db1")
+vb.ExecSQL("use db1")
+vb.ExecSQL("create table t1(id int)")
+vb.ExecSQL("alter table db1.t1 add column name varchar(255);")
+
+vb.Text()
+/* 
+output:
+CREATE DATABASE `db1`;
+CREATE TABLE `db1`.`t1` (`id` INT,`name` VARCHAR(255));
+*/
+```

cmd/sql-diff/main.go

@@ -0,0 +1,9 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println("hello world")
+}

virtualdb/error.go

@@ -0,0 +1,19 @@
+package virtualdb
+
+import "errors"
+
+const (
+	NotExistSchemaErrorPattern  = "not exist schema: %s"
+	DuplicateSchemaErrorPattern = "duplicate schema: %s"
+	NotExistTableErrorPattern   = "not exist table: %s.%s"
+	DuplicateTableErrorPattern  = "duplicate table: %s.%s"
+	NotExistColumnErrorPattern  = "not exist column %s in %s.%s"
+	DuplicateColumnErrorPattern = "duplicate column %s in %s.%s"
+	NotExistIndexErrorPattern   = "not exist index %s in %s.%s"
+	DuplicateIndexErrorPattern  = "duplicate index %s in %s.%s"
+)
+
+var (
+	NoPrimaryKeyError    = errors.New("no primary key")
+	ExistPrimaryKeyError = errors.New("primary key exists")
+)

virtualdb/util.go

@@ -0,0 +1,96 @@
+package virtualdb
+
+import (
+	"fmt"
+	"github.com/pingcap/parser"
+	"github.com/pingcap/parser/ast"
+	"github.com/pingcap/parser/format"
+	_ "github.com/pingcap/tidb/types/parser_driver"
+	"strings"
+)
+
+func restoreToSql(stmt ast.StmtNode) (string, error) {
+	var sb strings.Builder
+	ctx := format.NewRestoreCtx(format.DefaultRestoreFlags, &sb)
+	err := stmt.Restore(ctx)
+	if err != nil {
+		return "", err
+	}
+	return sb.String(), nil
+}
+
+// parseCreateTableStmt parse create table sql text to CreateTableStmt ast.
+func parseCreateTableStmt(sql string) (*ast.CreateTableStmt, error) {
+	t, err := parseOneSql(sql)
+	if err != nil {
+		return nil, err
+	}
+	createStmt, ok := t.(*ast.CreateTableStmt)
+	if !ok {
+		return nil, fmt.Errorf("stmt not support")
+	}
+	return createStmt, nil
+}
+
+func parseOneSql(sql string) (ast.StmtNode, error) {
+	p := parser.New()
+	stmt, err := p.ParseOneStmt(sql, "", "")
+	if err != nil {
+		return nil, err
+	}
+	return stmt, nil
+}
+
+func getAlterTableSpecByTp(specs []*ast.AlterTableSpec, ts ...ast.AlterTableType) []*ast.AlterTableSpec {
+	s := []*ast.AlterTableSpec{}
+	if specs == nil {
+		return s
+	}
+	for _, spec := range specs {
+		for _, tp := range ts {
+			if spec.Tp == tp {
+				s = append(s, spec)
+			}
+		}
+	}
+	return s
+}
+
+func hasOneInOptions(Options []*ast.ColumnOption, opTp ...ast.ColumnOptionType) bool {
+	// has one exists, return true
+	for _, tp := range opTp {
+		for _, op := range Options {
+			if tp == op.Tp {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func getPrimaryKey(stmt *ast.CreateTableStmt) (map[string]struct{}, bool) {
+	hasPk := false
+	pkColumnsName := map[string]struct{}{}
+	for _, constraint := range stmt.Constraints {
+		if constraint.Tp == ast.ConstraintPrimaryKey {
+			hasPk = true
+			for _, col := range constraint.Keys {
+				pkColumnsName[col.Column.Name.L] = struct{}{}
+			}
+		}
+	}
+	if !hasPk {
+		for _, col := range stmt.Cols {
+			if hasOneInOptions(col.Options, ast.ColumnOptionPrimaryKey) {
+				hasPk = true
+				pkColumnsName[col.Name.Name.L] = struct{}{}
+			}
+		}
+	}
+	return pkColumnsName, hasPk
+}
+
+func hasPrimaryKey(stmt *ast.CreateTableStmt) bool {
+	_, hasPk := getPrimaryKey(stmt)
+	return hasPk
+}