DbtPy对GBase 8s数据库的数据类型的支持

DbtPy对数据类型的支持

常用的数据类型如下：

字符类型

内置字符类型包括：char, nchar, varchar, nvarchar 和lvarchar
CHARACTER(n) 和 CHARACTER VARYING(n)这样的别名同样支持
参考代码：test_string_type.py

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create = """
create table tab_string(
    col1 char(32767),
    col2 nchar(32767),
    col3 varchar(255),
    col4 nvarchar(255),
    col5 lvarchar(32739)
)
"""
stmt = DbtPy.exec_immediate(conn, create)
insert = """
insert into tab_string(col1, col2, col3, col4, col5) values
('字符字段char类型','本地化字符字段nchar类型','可变长度字符字段varchar类型',
'本地化可变长度字符字段nvarchar类型','扩展可变长度字符字段lvarchar类型')
"""
stmt = DbtPy.exec_immediate(conn, insert)
 
select = "select * from tab_string"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_assoc(stmt)
while result :
    print("字段1的字节长度为：{} ,值为：\"{}\"". format(len(result['col1'].encode('utf8')),result['col1']))
    print("字段2的字节长度为：{} ,值为：\"{}\"". format(len(result['col2'].encode('utf8')),result['col2']))
    print("字段3的字节长度为：{} ,值为：\"{}\"". format(len(result['col3'].encode('utf8')),result['col3']))
    print("字段4的字节长度为：{} ,值为：\"{}\"". format(len(result['col4'].encode('utf8')),result['col4']))
    print("字段5的字节长度为：{} ,值为：\"{}\"". format(len(result['col5'].encode('utf8')),result['col5']))
    result = DbtPy.fetch_assoc(stmt)

数值类型

内置的数值类型包括：
整型：smallint, integer, int8, bigint
自增长整型：serial, serial8, bigserail
浮点型：smallfloat, float, decimal(P)
精确值型：decimal(P,S)
货币类型：money(P,S)
DEC(p,s)、NUMERIC(p,s)、INT和DOUBLE PRECISION这样的别名同样支持
参考代码：test_numeric_type.py

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create = """
create table tab_numeric(
    col1 serial not null,
    col2 smallint,
    col3 int,
    col4 int8,
    col5 bigint,
    col6 smallfloat,
    col7 float,
    col8 decimal(32,20),
    col9 decimal(32),
    colx money(32,20)
)
"""
stmt = DbtPy.exec_immediate(conn, create)
insert = """
insert into tab_numeric(col1, col2, col3, col4, col5, col6, col7, col8, col9, colx) values
(0,32767,2147483647,9223372036854775807,9223372036854775807,1234567890,12345678901234567890,123456789012.123456789,12345678901234567890123456789012,123456789012.123456789)
"""
stmt = DbtPy.exec_immediate(conn, insert)
 
select = "select * from tab_numeric"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_assoc(stmt)
while result :
    print("字段 1的类型serail         ,值为：{}" . format(result['col1']))
    print("字段 2的类型samllint       ,值为：{}" . format(result['col2']))
    print("字段 3的类型integer        ,值为：{}" . format(result['col3']))
    print("字段 4的类型int8           ,值为：{}" . format(result['col4']))
    print("字段 5的类型bigint         ,值为：{}" . format(result['col5']))
    print("字段 6的类型smallfloat     ,值为：{}" . format(result['col6']))
    print("字段 7的类型float          ,值为：{}" . format(result['col7']))
    print("字段 8的类型decimal(32,20) ,值为：{}" . format(result['col8']))
    print("字段 9的类型decimal(32)    ,值为：{}" . format(result['col9']))
    print("字段10的类型money(32,20)   ,值为：{}" . format(result['colx']))
    result = DbtPy.fetch_assoc(stmt)

日期时间型

日期型：date
日期时间型：datetime [first to last]
间隔类型：interval [first to list]
TIMESTAMP(n)这样的别名在部分版本中支持
interval类型部分支持（实现支持部分间隔类型）

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create = """
create table tab_datetime(
    col1 serial not null,
    col2 date,
    col3 datetime year to day,
    col4 datetime year to second,
    col5 datetime year to fraction(5),
    col6 interval day to minute
)
"""
stmt = DbtPy.exec_immediate(conn, create)
prepare = """
insert into tab_datetime(col1,col2,col3,col4,col5,col6) values(0,?,?,?,?,?)
"""
stmt = DbtPy.prepare(conn, prepare)
DbtPy.bind_param(stmt, 1, '2023-03-21')
DbtPy.bind_param(stmt, 2, '2023-03-21')
DbtPy.bind_param(stmt, 3, '2023-03-21 12:34:56')
DbtPy.bind_param(stmt, 4, '2023-03-21 12:34:56.98765')
DbtPy.bind_param(stmt, 5, '-3 12:13')
result = DbtPy.execute(stmt)
 
# 不支持interval year to month, day to second等
select = "select * from tab_datetime"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_assoc(stmt)
while result :
    print("字段 1的类型serail                  ,值为：{}" . format(result['col1']))
    print("字段 2的类型date                    ,值为：{}" . format(result['col2']))
    print("字段 3的类型datetime Y-m-d          ,值为：{}" . format(result['col3']))
    print("字段 4的类型datetime Y-m-d H:M:S    ,值为：{}" . format(result['col4']))
    print("字段 5的类型datetime Y-m-d H:M:S.F5 ,值为：{}" . format(result['col5']))
    print("字段 6的类型interval d H:M          ,值为：{}" . format(result['col6']))
    result = DbtPy.fetch_assoc(stmt)

大对象和智能大对象类型

大对象类型：byte、text
智能大对象类型：blob、 clob
限制：
text仅支持insert/update，不支持查询
clob仅支持使用函数操作(filetoclob(),locopy(),dbms_lob_new_clob())
byte支持使用bytes操作
blob支持使用bytes和函数操作(filetoblob(),locopy())
dbms_lob_new_clob函数:

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create function if not exists dbms_lob_new_clob (lvarchar)
returns clob with (not variant)
external name '$GBASEDBTDIR/extend/excompat.1.0/excompat.bld(dbms_lob_new_clob)' language c;

clob也可以使用blob相同的操作方式插入，获取时直接获取即可
注：fetch_assoc/fetch_tuple/fetch_both不建议获取2个以上lob类型

参考代码：test_lob_type.py

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create = """
create table tab_lob(
    col1 serial not null,
    col2 byte,
    col3 blob,
    col4 clob,
    col5 text
)
"""
stmt = DbtPy.exec_immediate(conn, create)
# 使用了dbms_log_new_clob函数将string转换为clob
# prepare = "insert into tab_lob(col1,col2,col3,col4,col5) values(0,?,?,dbms_lob_new_clob(?),?)"
prepare = "insert into tab_lob(col1,col2,col3,col4,col5) values(0,?,?,?,?)"
col2_byte = bytes('byte类型输入，最大支持2GB', encoding='UTF-8')
col3_blob = bytes('blob类型输入，最大支持4TB', encoding='UTF-8')
col4_str = 'clob类型输入'
col4_clob = bytes(col4_str, encoding='UTF-8')
col5_text = 'text类型输入'
stmt = DbtPy.prepare(conn, prepare)
DbtPy.bind_param(stmt,1, col2_byte, DbtPy.SQL_PARAM_INPUT)
DbtPy.bind_param(stmt,2, col3_blob, DbtPy.SQL_PARAM_INPUT)
DbtPy.bind_param(stmt,3, col4_clob, DbtPy.SQL_PARAM_INPUT)
DbtPy.bind_param(stmt,4, col5_text, DbtPy.SQL_PARAM_INPUT)
result = DbtPy.execute(stmt)
 
# text暂时还不支持获取操作
select = "select col1,col2,col3,col4 from tab_lob"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_both(stmt)
while result :
    print("字段1的值为：\"{}\"". format(result[0]))
    print("字段2的值为：\"{}\"". format(result[1].decode('UTF-8')))
    print("字段3的值为：\"{}\"". format(result[2].decode('UTF-8')))
    print("字段4的值为：\"{}\"". format(result[3]))
 
    result = DbtPy.fetch_both(stmt)

布尔类型

布尔类型：boolean
取值范围：'t'/1, 'f'/0, null(None)
参考代码：test_boolean_type.py

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create = """
create table tab_boolean(
    col1 serial not null,
    col2 boolean
)
"""
stmt = DbtPy.exec_immediate(conn, create)
prepare = """
insert into tab_boolean(col1,col2) values(0,?)
"""
stmt = DbtPy.prepare(conn, prepare)
DbtPy.bind_param(stmt, 1, True)
result = DbtPy.execute(stmt)
DbtPy.bind_param(stmt, 1, False)
result = DbtPy.execute(stmt)
DbtPy.bind_param(stmt, 1, None)
result = DbtPy.execute(stmt)
 
select = "select * from tab_boolean"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_assoc(stmt)
while result :
    print("字段 1的类型serail   ,值为：{}" . format(result['col1']))
    print("字段 2的类型boolean  ,值为：{}" . format(result['col2']))
    result = DbtPy.fetch_assoc(stmt)

扩展类型LIST

LIST类型：list(TYPE not null)
扩展类型查询结果为bytes类型，需要decode操作
参考代码：test_list_type.py

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create = """
create table tab_list(
    col1 serial not null,
    col2 LIST(varchar(20) not null)
)
"""
stmt = DbtPy.exec_immediate(conn, create)
prepare = """
insert into tab_list(col1,col2) values(0,?)
"""
col2_list = None
stmt = DbtPy.prepare(conn, prepare)
DbtPy.bind_param(stmt, 1, col2_list, DbtPy.SQL_PARAM_INPUT, DbtPy.SQL_CHAR, DbtPy.SQL_INFX_RC_COLLECTION)
col2_list = "LIST{'aaaa','bbbb','cccc'}"
result = DbtPy.execute(stmt,(col2_list,))
 
select = "select * from tab_list"
stmt = DbtPy.exec_immediate(conn, select)
result = DbtPy.fetch_assoc(stmt)
while result :
    print("字段 1的类型serail   ,值为：{}" . format(result['col1']))
    # LIST 类型以bytes输出, 需转码成字符串
    print("字段 2的类型list     ,值为：{}" . format(result['col2'].decode('UTF-8')))
    result = DbtPy.fetch_assoc(stmt)

注意
DbtPy使用的环境变量示例如下：

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export GBASEDBTDIR=/opt/gbase8s-odbc-driver
export CSDK_HOME=/opt/gbase8s-odbc-driver
export PATH=$GBASEDBTDIR/bin:$PATH
export LD_LIBRARY_PATH=$GBASEDBTDIR/lib:$GBASEDBTDIR/lib/cli:$GBASEDBTDIR/lib/esql:$LD_LIBRARY_PATH

参考代码：
test_dbtpy.tar.gz

标签: 数据类型, GBase, DbtPy

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