zModifyField_Proc (procedure)

• Type: PROCEDURE
• Deterministic: NO
• SQL data access: CONTAINS SQL

Parameters

#	Mode	Name	Type
1	IN	sColumnName	varchar(100)
2	IN	sTableName	varchar(100)
3	IN	sType	varchar(100)
4	IN	sDefault	varchar(100)
5	IN	sIsNull	varchar(100)
6	IN	sComment	varchar(255)

Body

Body is not pre-cached. To inspect: mysql --defaults-file=~/.my.cnf -e 'SHOW CREATE PROCEDUREzModifyFieldProc'._

Narrative

Business context: Maintenance / migration helper. Twin of zAddField_Proc: idempotent column-modifier that re-types an existing column (MODIFY COLUMN), used by Flyway scripts and upgrade SQLs to evolve a column's type / default / null-ability / comment without failing when the column is already absent.

What it does: SELECT DATABASE() INTO sTableSchema, lower-cases sType. Guards with IF EXISTS (SELECT * FROM information_schema.COLUMNS WHERE COLUMN_NAME=sColumnName AND TABLE_SCHEMA=sTableSchema AND TABLE_NAME=sTableName). When sDefault is '' picks a type-appropriate default ('', 0, 0.000000, b'0', now()); when non-empty formats per type (varchar quoted, int/decimal literal, bit as b'<val>', datetime literal). Builds ALTER TABLE \` MODIFY COLUMN `` and runs it throughPREPARE/EXECUTE. Nosalsalesorderslavecarve-out (unlikezAddField_Proc`).

Invocation: No DB-routine caller in the live catalog. Used by Flyway / upgrade scripts under xly-src/script/标版/upgrade/ (e.g. 20230210_消息、工作流、定时 模块_20230210.sql, 20220105-2751-保存、删除调过程/zAddFieldProc.sql, script/标版/20210323/zAddFieldScript.sql / zAddFieldProc.sql). Fires from the same upgrade execution paths as zAddField_Proc whenever a column needs reshaping.