以下的mysql语句如何在id_person和date_z上建立索引,并修改以下语句,以提高查询速度sql = """select date_d,count(*) from luzhi_jilu_all where id_person='{}' group by date_d order by date_d desc """.format(id_person)

在id_person和date_z上建立索引的语句如下：

CREATE INDEX idx_id_person_date_z ON luzhi_jilu_all (id_person, date_z);

修改后的查询语句如下：

SELECT date_d, COUNT(*) 
FROM luzhi_jilu_all 
WHERE id_person='{}' 
GROUP BY date_d 
ORDER BY date_d DESC 

请将大括号{}替换为实际的id_person值。这个查询语句能够在id_person和date_z上建立的索引的基础上提高查询速度。

相关问题

以下python语句sql = """ SELECT date_z, COUNT(*) + IFNULL(nn, 0) FROM ( SELECT id_person, date_z, date_finish FROM luzhi_jilu_all WHERE id_person = %s AND (date_z = date_finish OR date_finish IS NULL) ) AS t1 LEFT JOIN ( SELECT id_person, date_finish, COUNT(*) AS nn FROM luzhi_jilu_all GROUP BY id_person, date_finish ) AS t2 ON t1.id_person = t2.id_person AND t1.date_z = t2.date_finish GROUP BY date_z ORDER BY date_z DESC """ params = (id_person,) cs.execute(sql, params) jg = cs.fetchall()提示出现以下错误pymysql.err.InternalError: (1055, "Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 't2.nn' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by"),请检查错误,并修改

这个错误是由于 MySQL 的 sql_mode=only_full_group_by 模式导致的。在这种模式下，如果 SELECT 语句中的列不在 GROUP BY 子句中，那么这些列必须是聚合函数的参数，或者在 SELECT 子句中使用 IFNULL、CASE 等函数来进行处理。因为在 GROUP BY 子句中聚合分组依赖于 SELECT 子句中的列，如果 SELECT 子句中的列没有在 GROUP BY 子句中出现，那么这些列的值在聚合时是不确定的。

对于这段 SQL 语句，错误出现在 SELECT 子句中的第二个列，即 COUNT(*) + IFNULL(nn, 0)。这个列没有在 GROUP BY 子句中出现，也不是聚合函数的参数，因此需要使用一个聚合函数来处理它。你可以把这个列替换为 SUM(COUNT(*) + IFNULL(nn, 0))，这样就可以避免这个错误了。

修改后的 SQL 语句如下：

sql = """
SELECT date_z, SUM(COUNT(*) + IFNULL(nn, 0))
FROM (
SELECT id_person, date_z, date_finish
FROM luzhi_jilu_all
WHERE id_person = %s AND (date_z = date_finish OR date_finish IS NULL)
) AS t1
LEFT JOIN (
SELECT id_person, date_finish, COUNT(*) AS nn
FROM luzhi_jilu_all
GROUP BY id_person, date_finish
) AS t2 ON t1.id_person = t2.id_person AND t1.date_z = t2.date_finish
GROUP BY date_z
ORDER BY date_z DESC
"""

params = (id_person,)
cs.execute(sql, params)
jg = cs.fetchall()

优化以下python中三个mysql查询语句,得到三个独立的结果 sql = '''select id,name_work,date_z,isDelete,biaozhun from dubanworks where id_person='{0}' order by isDelete desc,id desc '''.format(id_person) co.to_sql(sql) jg1 = cs.fetchall() sql = '''select id,name_work,date_z,isDelete,biaozhun from dubanworks where id_fenguan like '#{0}#' order by isDelete desc,id desc '''.format(id_person) co.to_sql(sql) jg2 = cs.fetchall() sql = '''select id,name_work,date_z,isDelete,biaozhun from dubanworks where id_weijieshuo='#{0}#' order by isDelete desc,id desc '''.format(id_person) x = co.to_sql(sql) co.to_sql(sql) jg3 = cs.fetchall() data ={"A":jg1,"B",jg2,"C",jg3}

优化后的代码如下：

sql1 = '''SELECT id, name_work, date_z, isDelete, biaozhun FROM dubanworks WHERE id_person=%s ORDER BY isDelete DESC, id DESC'''
cs.execute(sql1, (id_person,))
jg1 = cs.fetchall()

sql2 = '''SELECT id, name_work, date_z, isDelete, biaozhun FROM dubanworks WHERE id_fenguan LIKE %s ORDER BY isDelete DESC, id DESC'''
cs.execute(sql2, ('#' + id_person + '#',))
jg2 = cs.fetchall()

sql3 = '''SELECT id, name_work, date_z, isDelete, biaozhun FROM dubanworks WHERE id_weijieshuo=%s ORDER BY isDelete DESC, id DESC'''
cs.execute(sql3, ('#' + id_person + '#',))
jg3 = cs.fetchall()

data = {"A": jg1, "B": jg2, "C": jg3}

这里使用了参数化查询，避免了SQL注入的风险。同时，将SQL语句拆分为三个独立的查询，使用不同的参数，避免了使用WHERE子句中的OR操作符。此外，使用了更加清晰的命名，使得代码更易读。