将SQL查询出来的数据作为一个张“表",之后根据这张“表”在进行条件查询的实例分析
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2022-06-16 15:06:48
sql语句演变一:
select ta.a_code, ta.b_code, ta.c_code, ta.a_name, ta.a_time,
tb.b_claz...
sql语句演变一:
select ta.a_code, ta.b_code, ta.c_code, ta.a_name, ta.a_time, tb.b_clazz, tc.c_model, td.d_good from tablea ta left join tableb tb on ta.a_code = tb.a_code left join tablec tc on ta.b_code = tc.b_code left join tabled td on ta.c_code = td.c_code
sql语句演变二:
select tab.a_code, tab.b_code, tab.c_code, tab.a_name, tab.a_time, tab.b_clazz, tab.c_model, tab.d_good from (select ta.a_code, ta.b_code, ta.c_code, ta.a_name, ta.a_time, tb.b_clazz, tc.c_model, td.d_good from tablea ta left join tableb tb on ta.a_code = tb.a_code left join tablec tc on ta.b_code = tc.b_code left join tabled td on ta.c_code = td.c_code) tab
sql语句演变三:
mybatis中的动态sql,条件查询,模糊匹配。
<select id="findmsg" resultmap="某一实体类对应的mapper.xml映射名"> select tab.a_code, tab.b_code, tab.c_code, tab.a_name, tab.a_time, tab.b_clazz, tab.c_model, tab.d_good from (select ta.a_code, ta.b_code, ta.c_code, ta.a_name, ta.a_time, tb.b_clazz, tc.c_model, td.d_good from tablea ta left join tableb tb on ta.a_code = tb.a_code left join tablec tc on ta.b_code = tc.b_code left join tabled td on ta.c_code = td.c_code) tab <where> <if test=" a_code != '' and a_code != null "> tab.a_code like concat('%', #{a_code}, '%') </if> <if test=" b_code != '' and b_code != null "> and tab.b_code like concat('%', #{b_code}, '%') </if> <if test=" c_model !='' and c_model != null "> and tab.c_model like concat('%', #{c_model}, '%') </if> <where> </select>
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