using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Linq;
using System.Net;
using NewLife.Collections;
using NewLife.Data;
using NewLife.Reflection;
namespace XCode.DataAccessLayer
{
class MySql : RemoteDb
{
#region 属性
/// <summary>返回数据库类型。</summary>
public override DatabaseType Type => DatabaseType.MySql;
private static DbProviderFactory _Factory;
/// <summary>工厂</summary>
public override DbProviderFactory Factory
{
get
{
if (_Factory == null)
{
lock (typeof(MySql))
{
//_Factory = GetProviderFactory("NewLife.MySql.dll", "NewLife.MySql.MySqlClientFactory") ??
// GetProviderFactory("MySql.Data.dll", "MySql.Data.MySqlClient.MySqlClientFactory");
// MewLife.MySql 在开发过程中，数据驱动下载站点没有它的包，暂时不支持下载
_Factory = GetProviderFactory(null, "NewLife.MySql.MySqlClientFactory", true, true) ??
GetProviderFactory("MySql.Data.dll", "MySql.Data.MySqlClient.MySqlClientFactory");
}
}
return _Factory;
}
}
const String Server_Key = "Server";
const String CharSet = "CharSet";
//const String AllowZeroDatetime = "Allow Zero Datetime";
const String MaxPoolSize = "MaxPoolSize";
const String Sslmode = "Sslmode";
protected override void OnSetConnectionString(ConnectionStringBuilder builder)
{
base.OnSetConnectionString(builder);
var key = builder[Server_Key];
if (key.EqualIgnoreCase(".", "localhost"))
{
//builder[Server_Key] = "127.0.0.1";
builder[Server_Key] = IPAddress.Loopback.ToString();
}
// 默认设置为utf8mb4，支持表情符
builder.TryAdd(CharSet, "utf8mb4");
//if (!builder.ContainsKey(AllowZeroDatetime)) builder[AllowZeroDatetime] = "True";
// 默认最大连接数1000
if (builder["Pooling"].ToBoolean()) builder.TryAdd(MaxPoolSize, "1000");
// 如未设置Sslmode，默认为none
if (builder[Sslmode] == null) builder.TryAdd(Sslmode, "none");
}
#endregion
#region 方法
/// <summary>创建数据库会话</summary>
/// <returns></returns>
protected override IDbSession OnCreateSession() => new MySqlSession(this);
/// <summary>创建元数据对象</summary>
/// <returns></returns>
protected override IMetaData OnCreateMetaData() => new MySqlMetaData();
public override Boolean Support(String providerName)
{
providerName = providerName.ToLower();
if (providerName.Contains("mysql.data.mysqlclient")) return true;
if (providerName.Contains("mysql")) return true;
return false;
}
#endregion
#region 分页
/// <summary>已重写。获取分页</summary>
/// <param name="sql">SQL语句</param>
/// <param name="startRowIndex">开始行，0表示第一行</param>
/// <param name="maximumRows">最大返回行数，0表示所有行</param>
/// <param name="keyColumn">主键列。用于not in分页</param>
/// <returns></returns>
public override String PageSplit(String sql, Int64 startRowIndex, Int64 maximumRows, String keyColumn) => PageSplitByLimit(sql, startRowIndex, maximumRows);
/// <summary>构造分页SQL</summary>
/// <param name="builder">查询生成器</param>
/// <param name="startRowIndex">开始行，0表示第一行</param>
/// <param name="maximumRows">最大返回行数，0表示所有行</param>
/// <returns>分页SQL</returns>
public override SelectBuilder PageSplit(SelectBuilder builder, Int64 startRowIndex, Int64 maximumRows) => PageSplitByLimit(builder, startRowIndex, maximumRows);
/// <summary>已重写。获取分页</summary>
/// <param name="sql">SQL语句</param>
/// <param name="startRowIndex">开始行，0表示第一行</param>
/// <param name="maximumRows">最大返回行数，0表示所有行</param>
/// <returns></returns>
public static String PageSplitByLimit(String sql, Int64 startRowIndex, Int64 maximumRows)
{
// 从第一行开始，不需要分页
if (startRowIndex <= 0)
{
if (maximumRows < 1) return sql;
return "{0} limit {1}".F(sql, maximumRows);
}
if (maximumRows < 1) throw new NotSupportedException("不支持取第几条数据之后的所有数据！");
return "{0} limit {1}, {2}".F(sql, startRowIndex, maximumRows);
}
/// <summary>构造分页SQL</summary>
/// <param name="builder">查询生成器</param>
/// <param name="startRowIndex">开始行，0表示第一行</param>
/// <param name="maximumRows">最大返回行数，0表示所有行</param>
/// <returns>分页SQL</returns>
public static SelectBuilder PageSplitByLimit(SelectBuilder builder, Int64 startRowIndex, Int64 maximumRows)
{
// 从第一行开始，不需要分页
if (startRowIndex <= 0)
{
if (maximumRows > 0) builder.Limit = "limit {0}".F(maximumRows);
return builder;
}
if (maximumRows < 1) throw new NotSupportedException("不支持取第几条数据之后的所有数据！");
builder.Limit = "limit {0}, {1}".F(startRowIndex, maximumRows);
return builder;
}
#endregion
#region 数据库特性
protected override String ReservedWordsStr
{
get
{
return "ACCESSIBLE,ADD,ALL,ALTER,ANALYZE,AND,AS,ASC,ASENSITIVE,BEFORE,BETWEEN,BIGINT,BINARY,BLOB,BOTH,BY,CALL,CASCADE,CASE,CHANGE,CHAR,CHARACTER,CHECK,COLLATE,COLUMN,CONDITION,CONNECTION,CONSTRAINT,CONTINUE,CONTRIBUTORS,CONVERT,CREATE,CROSS,CURRENT_DATE,CURRENT_TIME,CURRENT_TIMESTAMP,CURRENT_USER,CURSOR,DATABASE,DATABASES,DAY_HOUR,DAY_MICROSECOND,DAY_MINUTE,DAY_SECOND,DEC,DECIMAL,DECLARE,DEFAULT,DELAYED,DELETE,DESC,DESCRIBE,DETERMINISTIC,DISTINCT,DISTINCTROW,DIV,DOUBLE,DROP,DUAL,EACH,ELSE,ELSEIF,ENCLOSED,ESCAPED,EXISTS,EXIT,EXPLAIN,FALSE,FETCH,FLOAT,FLOAT4,FLOAT8,FOR,FORCE,FOREIGN,FROM,FULLTEXT,GRANT,GROUP,HAVING,HIGH_PRIORITY,HOUR_MICROSECOND,HOUR_MINUTE,HOUR_SECOND,IF,IGNORE,IN,INDEX,INFILE,INNER,INOUT,INSENSITIVE,INSERT,INT,INT1,INT2,INT3,INT4,INT8,INTEGER,INTERVAL,INTO,IS,ITERATE,JOIN,KEY,KEYS,KILL,LEADING,LEAVE,LEFT,LIKE,LIMIT,LINEAR,LINES,LOAD,LOCALTIME,LOCALTIMESTAMP,LOCK,LONG,LONGBLOB,LONGTEXT,LOOP,LOW_PRIORITY,MATCH,MEDIUMBLOB,MEDIUMINT,MEDIUMTEXT,MIDDLEINT,MINUTE_MICROSECOND,MINUTE_SECOND,MOD,MODIFIES,NATURAL,NOT,NO_WRITE_TO_BINLOG,NULL,NUMERIC,ON,OPTIMIZE,OPTION,OPTIONALLY,OR,ORDER,OUT,OUTER,OUTFILE,PRECISION,PRIMARY,PROCEDURE,PURGE,RANGE,READ,READS,READ_ONLY,READ_WRITE,REAL,REFERENCES,REGEXP,RELEASE,RENAME,REPEAT,REPLACE,REQUIRE,RESTRICT,RETURN,REVOKE,RIGHT,RLIKE,SCHEMA,SCHEMAS,SECOND_MICROSECOND,SELECT,SENSITIVE,SEPARATOR,SET,SHOW,SMALLINT,SPATIAL,SPECIFIC,SQL,SQLEXCEPTION,SQLSTATE,SQLWARNING,SQL_BIG_RESULT,SQL_CALC_FOUND_ROWS,SQL_SMALL_RESULT,SSL,STARTING,STRAIGHT_JOIN,TABLE,TERMINATED,THEN,TINYBLOB,TINYINT,TINYTEXT,TO,TRAILING,TRIGGER,TRUE,UNDO,UNION,UNIQUE,UNLOCK,UNSIGNED,UPDATE,UPGRADE,USAGE,USE,USING,UTC_DATE,UTC_TIME,UTC_TIMESTAMP,VALUES,VARBINARY,VARCHAR,VARCHARACTER,VARYING,WHEN,WHERE,WHILE,WITH,WRITE,X509,XOR,YEAR_MONTH,ZEROFILL," +
"LOG,User,Role,Admin,Rank";
}
}
/// <summary>格式化关键字</summary>
/// <param name="keyWord">关键字</param>
/// <returns></returns>
public override String FormatKeyWord(String keyWord)
{
//if (String.IsNullOrEmpty(keyWord)) throw new ArgumentNullException("keyWord");
if (keyWord.IsNullOrEmpty()) return keyWord;
if (keyWord.StartsWith("`") && keyWord.EndsWith("`")) return keyWord;
return $"`{keyWord}`";
}
/// <summary>格式化数据为SQL数据</summary>
/// <param name="field">字段</param>
/// <param name="value">数值</param>
/// <returns></returns>
public override String FormatValue(IDataColumn field, Object value)
{
var code = System.Type.GetTypeCode(field.DataType);
if (code == TypeCode.String)
{
if (value == null)
return field.Nullable ? "null" : "''";
return "'" + value.ToString()
.Replace("\\", "\\\\")//反斜杠需要这样才能插入到数据库
.Replace("'", @"\'") + "'";
}
else if (code == TypeCode.Boolean)
{
var v = value.ToBoolean();
if (field.Table != null && EnumTables.Contains(field.Table.TableName))
return v ? "'Y'" : "'N'";
else
return v ? "1" : "0";
}
return base.FormatValue(field, value);
}
/// <summary>长文本长度</summary>
public override Int32 LongTextLength => 4000;
internal protected override String ParamPrefix => "?";
/// <summary>创建参数</summary>
/// <param name="name">名称</param>
/// <param name="value">值</param>
/// <param name="field">字段</param>
/// <returns></returns>
public override IDataParameter CreateParameter(String name, Object value, IDataColumn field = null)
{
var dp = base.CreateParameter(name, value, field);
var type = field?.DataType;
if (type == null) type = value?.GetType();
// MySql的枚举要用 DbType.String
if (type == typeof(Boolean))
{
var v = value.ToBoolean();
if (field?.Table != null && EnumTables.Contains(field.Table.TableName))
{
dp.DbType = DbType.String;
dp.Value = value.ToBoolean() ? 'Y' : 'N';
}
else
{
dp.DbType = DbType.Int16;
dp.Value = v ? 1 : 0;
}
}
return dp;
}
/// <summary>系统数据库名</summary>
public override String SystemDatabaseName => "mysql";
/// <summary>字符串相加</summary>
/// <param name="left"></param>
/// <param name="right"></param>
/// <returns></returns>
public override String StringConcat(String left, String right) => String.Format("concat({0},{1})", (!String.IsNullOrEmpty(left) ? left : "\'\'"), (!String.IsNullOrEmpty(right) ? right : "\'\'"));
#endregion
#region 跨版本兼容
/// <summary>采用枚举来表示布尔型的数据表。由正向工程赋值</summary>
public ICollection<String> EnumTables { get; } = new HashSet<String>(StringComparer.OrdinalIgnoreCase);
#endregion
}
/// <summary>MySql数据库</summary>
internal class MySqlSession : RemoteDbSession
{
#region 构造函数
public MySqlSession(IDatabase db) : base(db) { }
#endregion
#region 快速查询单表记录数
/// <summary>快速查询单表记录数，大数据量时，稍有偏差。</summary>
/// <param name="tableName"></param>
/// <returns></returns>
public override Int64 QueryCountFast(String tableName)
{
tableName = tableName.Trim().Trim('`', '`').Trim();
var db = Database.DatabaseName;
var sql = $"select table_rows from information_schema.tables where table_schema='{db}' and table_name='{tableName}'";
return ExecuteScalar<Int64>(sql);
}
#endregion
#region 基本方法 查询/执行
/// <summary>执行插入语句并返回新增行的自动编号</summary>
/// <param name="sql">SQL语句</param>
/// <param name="type">命令类型，默认SQL文本</param>
/// <param name="ps">命令参数</param>
/// <returns>新增行的自动编号</returns>
public override Int64 InsertAndGetIdentity(String sql, CommandType type = CommandType.Text, params IDataParameter[] ps)
{
sql += ";Select LAST_INSERT_ID()";
return base.InsertAndGetIdentity(sql, type, ps);
}
#endregion
#region 批量操作
/*
insert into stat (siteid,statdate,`count`,cost,createtime,updatetime) values
(1,'2018-08-11 09:34:00',1,123,now(),now()),
(2,'2018-08-11 09:34:00',1,456,now(),now()),
(3,'2018-08-11 09:34:00',1,789,now(),now()),
(2,'2018-08-11 09:34:00',1,456,now(),now())
on duplicate key update
`count`=`count`+values(`count`),cost=cost+values(cost),
updatetime=values(updatetime);
*/
private String GetBatchSql(String tableName, IDataColumn[] columns, ICollection<String> updateColumns, ICollection<String> addColumns, IEnumerable<IIndexAccessor> list)
{
var sb = Pool.StringBuilder.Get();
var db = Database as DbBase;
// 字段列表
//if (columns == null) columns = table.Columns.ToArray();
sb.AppendFormat("Insert Into {0}(", db.FormatTableName(tableName));
foreach (var dc in columns)
{
// 取消对主键的过滤，避免列名和值无法一一对应的问题
//if (dc.Identity) continue;
sb.Append(db.FormatName(dc.ColumnName));
sb.Append(",");
}
sb.Length--;
sb.Append(")");
// 值列表
sb.Append(" Values");
// 优化支持DbTable
if (list.FirstOrDefault() is DbRow)
{
// 提前把列名转为索引，然后根据索引找数据
DbTable dt = null;
Int32[] ids = null;
foreach (DbRow dr in list)
{
if (dr.Table != dt)
{
dt = dr.Table;
var cs = new List<Int32>();
foreach (var dc in columns)
{
if (dc.Identity)
cs.Add(0);
else
cs.Add(dt.GetColumn(dc.ColumnName));
}
ids = cs.ToArray();
}
sb.Append("(");
var row = dt.Rows[dr.Index];
for (var i = 0; i < columns.Length; i++)
{
var dc = columns[i];
//if (dc.Identity) continue;
var value = row[ids[i]];
sb.Append(db.FormatValue(dc, value));
sb.Append(",");
}
sb.Length--;
sb.Append("),");
}
}
else
{
foreach (var entity in list)
{
sb.Append("(");
foreach (var dc in columns)
{
//if (dc.Identity) continue;
var value = entity[dc.Name];
sb.Append(db.FormatValue(dc, value));
sb.Append(",");
}
sb.Length--;
sb.Append("),");
}
}
sb.Length--;
// 重复键执行update
if ((updateColumns != null && updateColumns.Count > 0) || (addColumns != null && addColumns.Count > 0))
{
sb.Append(" On Duplicate Key Update ");
if (updateColumns != null && updateColumns.Count > 0)
{
foreach (var dc in columns)
{
if (dc.Identity || dc.PrimaryKey) continue;
if (updateColumns.Contains(dc.Name) && (addColumns == null || !addColumns.Contains(dc.Name)))
sb.AppendFormat("{0}=Values({0}),", db.FormatName(dc.ColumnName));
}
sb.Length--;
}
if (addColumns != null && addColumns.Count > 0)
{
sb.Append(",");
foreach (var dc in columns)
{
if (dc.Identity || dc.PrimaryKey) continue;
if (addColumns.Contains(dc.Name))
sb.AppendFormat("{0}={0}+Values({0}),", db.FormatName(dc.ColumnName));
}
sb.Length--;
}
}
return sb.Put(true);
}
public override Int32 Insert(String tableName, IDataColumn[] columns, IEnumerable<IIndexAccessor> list)
{
// 分批
var batchSize = 10_000;
var rs = 0;
for (var i = 0; i < list.Count();)
{
var es = list.Skip(i).Take(batchSize).ToList();
var sql = GetBatchSql(tableName, columns, null, null, es);
rs += Execute(sql);
i += es.Count;
}
return rs;
}
public override Int32 Upsert(String tableName, IDataColumn[] columns, ICollection<String> updateColumns, ICollection<String> addColumns, IEnumerable<IIndexAccessor> list)
{
// 分批
var batchSize = 10_000;
var rs = 0;
for (var i = 0; i < list.Count();)
{
var es = list.Skip(i).Take(batchSize).ToList();
var sql = GetBatchSql(tableName, columns, updateColumns, addColumns, es);
rs += Execute(sql);
i += es.Count;
}
return rs;
}
#endregion
}
/// <summary>MySql元数据</summary>
class MySqlMetaData : RemoteDbMetaData
{
public MySqlMetaData() => Types = _DataTypes;
#region 数据类型
protected override List<KeyValuePair<Type, Type>> FieldTypeMaps
{
get
{
if (_FieldTypeMaps == null)
{
var list = base.FieldTypeMaps;
if (!list.Any(e => e.Key == typeof(Byte) && e.Value == typeof(Boolean)))
list.Add(new KeyValuePair<Type, Type>(typeof(Byte), typeof(Boolean)));
}
return base.FieldTypeMaps;
}
}
/// <summary>数据类型映射</summary>
private static Dictionary<Type, String[]> _DataTypes = new Dictionary<Type, String[]>
{
{ typeof(Byte[]), new String[] { "BLOB", "TINYBLOB", "MEDIUMBLOB", "LONGBLOB", "binary({0})", "varbinary({0})" } },
//{ typeof(TimeSpan), new String[] { "TIME" } },
//{ typeof(SByte), new String[] { "TINYINT" } },
{ typeof(Byte), new String[] { "TINYINT", "TINYINT UNSIGNED" } },
{ typeof(Int16), new String[] { "SMALLINT", "SMALLINT UNSIGNED" } },
//{ typeof(UInt16), new String[] { "SMALLINT UNSIGNED" } },
{ typeof(Int32), new String[] { "INT", "YEAR", "MEDIUMINT", "MEDIUMINT UNSIGNED", "INT UNSIGNED" } },
//{ typeof(UInt32), new String[] { "MEDIUMINT UNSIGNED", "INT UNSIGNED" } },
{ typeof(Int64), new String[] { "BIGINT", "BIT", "BIGINT UNSIGNED" } },
//{ typeof(UInt64), new String[] { "BIT", "BIGINT UNSIGNED" } },
{ typeof(Single), new String[] { "FLOAT" } },
{ typeof(Double), new String[] { "DOUBLE" } },
{ typeof(Decimal), new String[] { "DECIMAL({0}, {1})" } },
{ typeof(DateTime), new String[] { "DATETIME", "DATE", "TIMESTAMP", "TIME" } },
{ typeof(String), new String[] { "NVARCHAR({0})", "LONGTEXT", "TEXT", "CHAR({0})", "NCHAR({0})", "VARCHAR({0})", "SET", "ENUM", "TINYTEXT", "TEXT", "MEDIUMTEXT" } },
{ typeof(Boolean), new String[] { "TINYINT" } },
};
#endregion
#region 架构
protected override List<IDataTable> OnGetTables(String[] names)
{
var ss = Database.CreateSession();
var db = Database.DatabaseName;
var sql = $"SHOW TABLE STATUS FROM `{db}`";
var dt = ss.Query(sql, null);
if (dt.Rows.Count == 0) return null;
var list = new List<IDataTable>();
var hs = new HashSet<String>(names ?? new String[0], StringComparer.OrdinalIgnoreCase);
// 所有表
foreach (var dr in dt)
{
var name = dr["Name"] + "";
if (name.IsNullOrEmpty() || hs.Count > 0 && !hs.Contains(name)) continue;
var table = DAL.CreateTable();
table.TableName = name;
table.Description = dr["Comment"] + "";
#region 字段
sql = $"SHOW FULL COLUMNS FROM `{db}`.`{name}`";
var dcs = ss.Query(sql, null);
foreach (var dc in dcs)
{
var field = table.CreateColumn();
field.ColumnName = dc["Field"] + "";
field.RawType = dc["Type"] + "";
field.DataType = GetDataType(field.RawType);
field.Description = dc["Comment"] + "";
if (dc["Extra"] + "" == "auto_increment") field.Identity = true;
if (dc["Key"] + "" == "PRI") field.PrimaryKey = true;
if (dc["Null"] + "" == "YES") field.Nullable = true;
field.Length = field.RawType.Substring("(", ")").ToInt();
if (field.DataType == null)
{
if (field.RawType.StartsWithIgnoreCase("varchar", "nvarchar")) field.DataType = typeof(String);
}
// MySql中没有布尔型，这里处理YN枚举作为布尔型
if (field.RawType == "enum('N','Y')" || field.RawType == "enum('Y','N')") field.DataType = typeof(Boolean);
table.Columns.Add(field);
}
#endregion
#region 索引
sql = $"SHOW INDEX FROM `{db}`.`{name}`";
var dis = ss.Query(sql, null);
foreach (var dr2 in dis)
{
var dname = dr2["Key_name"] + "";
var di = table.Indexes.FirstOrDefault(e => e.Name == dname) ?? table.CreateIndex();
di.Name = dname;
di.Unique = dr2.Get<Int32>("Non_unique") == 0;
var cname = dr2.Get<String>("Column_name");
var cs = new List<String>();
if (di.Columns != null && di.Columns.Length > 0) cs.AddRange(di.Columns);
cs.Add(cname);
di.Columns = cs.ToArray();
table.Indexes.Add(di);
}
#endregion
// 修正关系数据
table.Fix();
list.Add(table);
}
// 找到使用枚举作为布尔型的旧表
var es = (Database as MySql).EnumTables;
foreach (var table in list)
{
if (!es.Contains(table.TableName))
{
var dc = table.Columns.FirstOrDefault(c => c.DataType == typeof(Boolean)
&& c.RawType.EqualIgnoreCase("enum('N','Y')", "enum('Y','N')"));
if (dc != null)
{
es.Add(table.TableName);
WriteLog("发现MySql中旧格式的布尔型字段 {0} {1}", table.TableName, dc);
}
}
}
return list;
}
public override String FieldClause(IDataColumn field, Boolean onlyDefine)
{
var sql = base.FieldClause(field, onlyDefine);
// 加上注释
if (!String.IsNullOrEmpty(field.Description)) sql = $"{sql} COMMENT '{field.Description}'";
return sql;
}
protected override String GetFieldConstraints(IDataColumn field, Boolean onlyDefine)
{
String str = null;
if (!field.Nullable) str = " NOT NULL";
if (field.Identity) str = " NOT NULL AUTO_INCREMENT";
return str;
}
#endregion
#region 反向工程
protected override Boolean DatabaseExist(String databaseName)
{
var dt = GetSchema(_.Databases, new String[] { databaseName });
return dt != null && dt.Rows != null && dt.Rows.Count > 0;
}
public override String CreateDatabaseSQL(String dbname, String file) => base.CreateDatabaseSQL(dbname, file) + " DEFAULT CHARACTER SET utf8mb4";
public override String DropDatabaseSQL(String dbname) => $"Drop Database If Exists {FormatName(dbname)}";
public override String CreateTableSQL(IDataTable table)
{
var fs = new List<IDataColumn>(table.Columns);
//var sb = new StringBuilder(32 + fs.Count * 20);
var sb = Pool.StringBuilder.Get();
var pks = new List<String>();
sb.AppendFormat("Create Table If Not Exists {0}(", FormatName(table.TableName));
for (var i = 0; i < fs.Count; i++)
{
sb.AppendLine();
sb.Append("\t");
sb.Append(FieldClause(fs[i], true));
if (i < fs.Count - 1) sb.Append(",");
if (fs[i].PrimaryKey) pks.Add(FormatName(fs[i].ColumnName));
}
// 如果有自增，则自增必须作为主键
foreach (var item in table.Columns)
{
if (item.Identity && !item.PrimaryKey)
{
pks.Clear();
pks.Add(FormatName(item.ColumnName));
break;
}
}
if (pks.Count > 0)
{
sb.AppendLine(",");
sb.AppendFormat("\tPrimary Key ({0})", String.Join(",", pks.ToArray()));
}
sb.AppendLine();
sb.Append(")");
// 引擎和编码
//sb.Append(" ENGINE=InnoDB");
sb.Append(" DEFAULT CHARSET=utf8mb4");
sb.Append(";");
return sb.Put(true);
}
public override String AddTableDescriptionSQL(IDataTable table)
{
if (String.IsNullOrEmpty(table.Description)) return null;
return $"Alter Table {FormatName(table.TableName)} Comment '{table.Description}'";
}
public override String AlterColumnSQL(IDataColumn field, IDataColumn oldfield) => $"Alter Table {FormatName(field.Table.TableName)} Modify Column {FieldClause(field, false)}";
public override String AddColumnDescriptionSQL(IDataColumn field)
{
// 返回String.Empty表示已经在别的SQL中处理
return String.Empty;
}
#endregion
}
}
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