https://www.zhangshuxian.top/article/102
SELECT
CONCAT("ALTER TABLE ",TABLE_NAME," MODIFY COLUMN ",COLUMN_NAME," ",COLUMN_TYPE,(case when IS_NULLABLE = "NO" THEN " NOT NULL" ELSE "" END)," DEFAULT 0 COMMENT '",COLUMN_COMMENT,"';") AS 'sql',
TABLE_SCHEMA AS '库名',
TABLE_NAME AS '表名',
COLUMN_NAME AS '列名',
ORDINAL_POSITION AS '列的排列顺序',
COLUMN_DEFAULT AS '默认值',
IS_NULLABLE AS '是否为空',
DATA_TYPE AS '数据类型',
CHARACTER_MAXIMUM_LENGTH AS '字符最大长度',
NUMERIC_PRECISION AS '数值精度(最大位数)',
NUMERIC_SCALE AS '小数精度',
COLUMN_TYPE AS '列类型',
COLUMN_KEY 'KEY',
EXTRA AS '额外说明',
COLUMN_COMMENT AS '注释'
FROM
information_schema.`COLUMNS`
WHERE
TABLE_SCHEMA = 'zxcrm-demo'
AND DATA_TYPE = 'decimal'
AND COLUMN_DEFAULT IS NULL and IS_NULLABLE = "NO";