Oracle数据库批量变更字段类型的实现步骤

-- 生成索引
SELECT T.TABLE_NAME, --表名
T.INDEX_NAME, --索引名
I.UNIQUENESS, --是否非空
I.INDEX_TYPE, --索引类型
C.CONSTRAINT_TYPE, --键类型
WM_CONCAT(T.COLUMN_NAME) COLS,
 
'ALTER TABLE ' || T.TABLE_NAME || ' DROP CONSTRAINT ' || T.INDEX_NAME ||';' 删除索引 ,
 
(CASE
WHEN C.CONSTRAINT_TYPE = 'P' OR C.CONSTRAINT_TYPE = 'R' THEN --主键和外键创建脚本拼接
'ALTER TABLE ' || T.TABLE_NAME || ' ADD CONSTRAINT ' ||
T.INDEX_NAME || (CASE
WHEN C.CONSTRAINT_TYPE = 'P' THEN
' PRIMARY KEY ('
ELSE
' FOREIGN KEY ('
END) || WM_CONCAT(T.COLUMN_NAME) || ');'
ELSE --索引创建脚本拼接
'CREATE ' || (CASE
WHEN I.UNIQUENESS = 'UNIQUE' THEN
I.UNIQUENESS || ' '
ELSE
CASE
WHEN I.INDEX_TYPE = 'NORMAL' THEN
''
ELSE
I.INDEX_TYPE || ' '
END
END) || 'INDEX ' || T.INDEX_NAME || ' ON ' || T.TABLE_NAME || '(' ||
WM_CONCAT(COLUMN_NAME) || ');'
END) 添加索引 
FROM USER_IND_COLUMNS T, USER_INDEXES I, USER_CONSTRAINTS C
WHERE T.INDEX_NAME = I.INDEX_NAME
AND T.INDEX_NAME = C.CONSTRAINT_NAME(+)--自建表规则（只查询自己创建的表【我的建表规则以TB_开头】，排除系统表）
AND I.INDEX_TYPE != 'FUNCTION-BASED NORMAL' --排除基于函数的索引
GROUP BY T.TABLE_NAME,
T.INDEX_NAME,
I.UNIQUENESS,
I.INDEX_TYPE,
C.CONSTRAINT_TYPE;
 

 
select 
 x."fieldType",
'alter table '||x."tableName"||' add '||c.column_name||'_U2 '||
case LOWER(x."fieldType")
when 'dateTime' then 'date'  
when 'decimal'  then 'number(18,2)'
when 'tring'  then 'VARCHAR2(100)'
when 'int16'  then 'number(5)'
when 'int'  then 'number(9)'
when 'int32'  then 'number(9)'
when 'int64'  then 'number(19)'
else  '异常类型'
end ||';
update '||x."tableName"||' set '||c.column_name||'_U2='|| case when  c.column_name ='ZFID' then f_tonumber(SUBSTR(ZFID, 1,8)) else  c.column_name end  ||';
alter table '||x."tableName"||'  drop column '||c.column_name||';
alter table '||x."tableName"||' rename column '||c.column_name||'_U2 to '||c.column_name||';' s,
 
-- 'alter table '||x."tableName"||' modify '||x."fieldName"||' varchar2(50);' sql,
x."id",x."fieldName" , x."tableName",lower( c.data_type) 表类型,
lower(case when to_char( x."fieldType") like 'E_%' then 'int' else x."fieldType" end ) 实体类型,
x."fieldName",x."className",x."nameSpace",x."createDate" 
from user_tab_columns  c  
inner join XT_CLASS x 
on c.table_name = x."tableName" and c.column_name = x."fieldName"
where  1=1 and X."nameSpace"='RCSCloud.Models'  and  lower(x."tableName") not like 'v_%'

CREATE TABLE "XT_CLASS" 
   (	"tableName" VARCHAR2(50) NOT NULL ENABLE, 
	"fieldName" VARCHAR2(50) NOT NULL ENABLE, 
	"fieldTitle" VARCHAR2(255), 
	"fieldType" VARCHAR2(50), 
	"className" VARCHAR2(50), 
	"nameSpace" VARCHAR2(255), 
	"createDate" DATE, 
	"id" NUMBER(11,0) NOT NULL ENABLE
   ) SEGMENT CREATION IMMEDIATE 
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "IOTDATA"