MySQL Data Types (Version 8.0) In MySQL there are three main data types: string, numeric, and date and time. String Data Types Data typeDescription CHAR(size)A FIXED length string (can contain letters, numbers, and special characters). Thesizeparameter specifies the column length in characters...
id: This column is of the DECIMAL data type. DECIMAL is used for numeric data with a fixed precision and scale. It is designated as the PRIMARY KEY for the table, implying that each value in this column must be unique and not null. col1: This column is of the BINARY data type with...
, c.DATA_TYPE columnType -- 字段类型 varchar之类的 , c.DATA_LENGTH columnLength -- 以字符为单位的最大长度 , -1 columnOctetLength -- 以字节为单位的最大长度 , c.DATA_PRECISION columnNumberPrecision -- 数字类型整数位长度 , c.DATA_SCALE columnNumberScale -- 数字小数位长度 , c.DATA_DEFAU...
SQL data types define the type of value that can be stored in a table column. For example, if you want a column to store only integer values, you can define its data type as INT. SQL data types can be broadly divided into the following categories. Numeric data types such as: INT, ...
SQLINTEGER cbSQLDataType; SQLINTEGER cbOrdinalPosition; int main() { SQLHENV henv; SQLHDBC hdbc; SQLHSTMT hstmt = 0; SQLRETURN retcode; char* pdsn = "MySQL8030"; char* puid = "root"; char* ppwd = "databasepassword"; char* tablename = "testcolumntypes"; ...
The syntax for SQL Data Types is: CREATETABLEtable_name ( column1_name datatype1, column2_name datatype2, column3_name datatype3, ... ); Here, column1_name,column2_name,column3_name,...are the names of the columns datatype1,datatype2,datatype3,...are the data types such asINT...
Table 1. SQL Data Types Mapped to C/C++ Declarations SQL Column TypeC/C++ Data TypeSQL Column Type Description SMALLINTsqlint16 SQLUDF_SMALLINT16-bit signed integer INTEGERsqlint32 SQLUDF_INTEGER32-bit signed integer BIGINTsqlint64 SQLUDF_BIGINT64-bit signed integer ...
mysql.com/doc/refman/5.7/en/column-count-limit.html) 存储: varchar类型存储数据的真实内容,不会用空格填充,如果'ab ',尾部的空格也会被存起来 强调:varchar类型会在真实数据前加1-2Bytes的前缀,该前缀用来表示真实数据的bytes字节数(1-2Bytes最大表示65535个数字,正好符合mysql对row的最大字节限制,即已经...
COLUMN_NAMEnvarchar(128)資料行名稱。 ORDINAL_POSITIONint資料行識別碼。 COLUMN_DEFAULTnvarchar(4000)數據行的預設值。 IS_NULLABLEvarchar(3)資料行的 Null 屬性。 如果此數據行允許 NULL,則此資料行會傳回 YES。 否則,它就會傳回 NO。 DATA_TYPEnvarchar(128)系統提供的資料類型。
int columnCount = rsmd.getColumnCount(); for (int i = 1; i <= columnCount; i++) { String s = rsmd.getColumnTypeName(i); System.out.println ("Column " + i + " is type " + s); } 8.4.2 带 IN 参数的 SQL 语句 在另一个可能的情况中,用户将发送带输入参数的 SQL 语句。这种情...