I had my stint (20 yrs) as a software developer and had used SDLC many times. I have a question on ‘your’ ..๓. Implementation คือ อนุวัติการ หมายถึง การดำเนินการให้เป็นผลตามบทบัญญัติแห่งอนุสัญญา.. (other stages are ‘familiar’). In software parlance (language, jargon, talk,…), the stages are problem identification (including users, operators, and stakeholders, entities and relationships, modelling); business analysis (this details ‘whys’ and ‘hows’ of problem(s) and solution options,… right down to proposed/selected solution(s) with detailed specifications, costing, benefits, …); build stage is after a ‘go ahead’ decision and fund/resources (usually a project team is setup to do the development of the system/solution); Testing (components testing are done in build stage) of ‘whole system’ to find if the application is working as specified and not causing problems to other areas of the ‘whole’ organization; after that if all is well then the ‘roll out’ or deployment is scheduled, training, manuals, recruitment, ‘shopfront’ for (new) system supports, …. Finally, the project team is dissolved with 1 or 2 members remain to support and maintain the new system.