1、 统计每列不同值出现的频数
SELECT column_name,count(*) num FROM table_name GROUP BY column_name
2、 查询所有字段名
select COLUMN_NAME,DATA_TYPE,COLUMN_COMMENT from information_schema.COLUMNS where table_name = '表名' and table_schema = '数据库名称';
3、 将查询结果插入表
4、 数据库的导入和导出
5、 数据库密码重置
6、 数据库去重查询
SELECT DISTINCT column_name FROM table_name
SELECT column_name FROM table_name GROUP BY column_name
7.去重留一
SELECT go_id, go_term, category,tax_id from ncbi_gene_go_hg_mm_main GROUP BY go_id HAVING count(*) > 1
